CL 5956051 introduced too many call != nil checks, so
attempt to improve this by splitting logic into three
distinct parts.

R=r
CC=golang-dev
https://golang.org/cl/6248048

image/png benchmarks:
benchmark                       old ns/op    new ns/op    delta
BenchmarkPaeth                         10            7  -29.21%
BenchmarkDecodeGray               2381745      2241620   -5.88%
BenchmarkDecodeNRGBAGradient      9535555      8835100   -7.35%
BenchmarkDecodeNRGBAOpaque        8189590      7611865   -7.05%
BenchmarkDecodePaletted           1300688      1301940   +0.10%
BenchmarkDecodeRGB                6760146      6317082   -6.55%
BenchmarkEncodePaletted           6048596      6122666   +1.22%
BenchmarkEncodeRGBOpaque         18891140     19474230   +3.09%
BenchmarkEncodeRGBA              78945350     78552600   -0.50%

Wall time for Denis Cheremisov's PNG-decoding program given in
https://groups.google.com/group/golang-nuts/browse_thread/thread/22aa8a05040fdd49
Before: 2.25s
After:  2.27s
Delta:  +1%

The same program, but with a different PNG input file
(http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png)
and only 100 iterations instead of 1000
Before: 4.78s
After:  4.42s
Delta:  -8%

R=rsc
CC=golang-dev
https://golang.org/cl/6242056

Ken pointed out that CL 5998043 was ugly code.
This should be better.

Fixes #3501.

R=ken2
CC=golang-dev
https://golang.org/cl/6258049

for expr1, expr2 = range slice
was assigning to expr1 and expr2 in sequence
instead of in parallel.  Now it assigns in parallel,
as it should.  This matters for things like
for i, x[i] = range slice.

Fixes #3464.

R=ken2
CC=golang-dev
https://golang.org/cl/6252048

This is from CL 5451105 but was dropped from that CL.
See also CL 6137051.

The only change compared to 5451105 is to check for
h != nil in reflect·mapiterinit; allowing use of nil maps
must have happened after that original CL.

Fixes #3573.

R=golang-dev, dave, r
CC=golang-dev
https://golang.org/cl/6215078

Fixes #3299

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6250056

Remove redundant checks for integration points.

Ignore null bytes in text.

Don't break out of foreign content for a <font> tag unless it
has a color, face, or size attribute.

Check for MathML text integration points when breaking out of
foreign content.

Pass two new tests.

R=nigeltao
CC=golang-dev
https://golang.org/cl/6256045

The bulk of the gains come from hoisting the modulo ops outside of
the inner loop.

Reducing the digest type from 8 bytes to 4 bytes gains another 1% on
the hash/adler32 micro-benchmark.

Benchmarks for $GOOS,$GOARCH = linux,amd64 below.

hash/adler32 benchmark:
benchmark             old ns/op    new ns/op    delta
BenchmarkAdler32KB         1660         1364  -17.83%

image/png benchmark:
benchmark                       old ns/op    new ns/op    delta
BenchmarkDecodeGray               2466909      2425539   -1.68%
BenchmarkDecodeNRGBAGradient      9884500      9751705   -1.34%
BenchmarkDecodeNRGBAOpaque        8511615      8379800   -1.55%
BenchmarkDecodePaletted           1366683      1330677   -2.63%
BenchmarkDecodeRGB                6987496      6884974   -1.47%
BenchmarkEncodePaletted           6292408      6040052   -4.01%
BenchmarkEncodeRGBOpaque         19780680     19178440   -3.04%
BenchmarkEncodeRGBA              80738600     79076800   -2.06%

Wall time for Denis Cheremisov's PNG-decoding program given in
https://groups.google.com/group/golang-nuts/browse_thread/thread/22aa8a05040fdd49
Before: 2.44s
After:  2.26s
Delta:  -7%

R=rsc
CC=golang-dev
https://golang.org/cl/6251044

Fixes #3580.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6252047

Fixes #3639.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/6243045

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6257050

When client fails to write a request is sends caller that error,
however server might have failed to read that request in the mean
time and replied with that error. When client then reads the
response the call would no longer be pending, so call will be nil

Handle this gracefully by discarding such server responses

R=golang-dev, r
CC=golang-dev, rsc
https://golang.org/cl/5956051

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6249052

* Eliminate bounds check on known small shifts.
* Rewrite x<<s | x>>(32-s) as a rotate (constant s).
* More aggressive (but still minimal) range analysis.

R=ken, dave, iant
CC=golang-dev
https://golang.org/cl/6209077

The previous attempt to explain this got it backwards (all the more reason to be
sad we couldn't make the two functions behave the same).

Fixes #3669.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6249051

Fixes #3295

R=adg, rsc, mike.rosset
CC=golang-dev
https://golang.org/cl/5796073

There's no need for the 16-bit arithmetic here,
and it tickles a long-standing compiler bug.
Fix the exp code not to use 16-bit math and
create an explicit test for the compiler bug.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6256048

R=ken2
CC=golang-dev
https://golang.org/cl/6254046

Part of fix for issue 3464.

R=golang-dev, rsc, mirtchovski, iant, r
CC=golang-dev
https://golang.org/cl/6246045

- interface methods appeared under VarDecl in search results
  (long-standing TODO)

- don't walk parts of AST which contain no indexable material
  (minor performance tuning)

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6228047

The documentation says so, but in the case of a normalized
integral Rat, the denominator was a new value. Changed the
internal representation to use an Int to represent the
denominator (with the sign ignored), so a reference to it
can always be returned.

Clarified documentation and added test cases.

Fixes #3521.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6237045

* Shift/rotate by constant doesn't have to stop subprop. (also in 8g)
* Remove redundant MOVLQZX instructions.
* An attempt at issuing loads early.
  Good for 0.5% on a good day, might not be worth keeping.
  Need to understand more about whether the x86
  looks ahead to what loads might be coming up.

R=ken2, ken
CC=golang-dev
https://golang.org/cl/6203091

        Fixes #3664.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6249048

Also bump MaxGcproc to 8.

benchmark             old ns/op    new ns/op    delta
Parser               3796323000   3763880000   -0.85%
Parser-2             3591752500   3518560250   -2.04%
Parser-4             3423825250   3334955250   -2.60%
Parser-8             3304585500   3267014750   -1.14%
Parser-16            3313615750   3286160500   -0.83%

Tree                  984128500    942501166   -4.23%
Tree-2                932564444    883266222   -5.29%
Tree-4                835831000    799912777   -4.30%
Tree-8                819238500    789717333   -3.73%
Tree-16               880837833    837840055   -5.13%

Tree2                 604698100    579716900   -4.13%
Tree2-2               372414500    356765200   -4.20%
Tree2-4               187488100    177455900   -5.56%
Tree2-8               136315300    102086700  -25.11%
Tree2-16               93725900     76705800  -22.18%

ParserPause           157441210    166202783   +5.56%
ParserPause-2          93842650     85199900   -9.21%
ParserPause-4          56844404     53535684   -5.82%
ParserPause-8          35739446     30767613  -16.15%
ParserPause-16         32718255     27212441  -16.83%

TreePause              29610557     29787725   +0.60%
TreePause-2            24001659     20674421  -13.86%
TreePause-4            15114887     12842781  -15.03%
TreePause-8            13128725     10741747  -22.22%
TreePause-16           16131360     12506901  -22.47%

Tree2Pause           2673350920   2651045280   -0.83%
Tree2Pause-2         1796999200   1709350040   -4.88%
Tree2Pause-4         1163553320   1090706480   -6.67%
Tree2Pause-8          987032520    858916360  -25.11%
Tree2Pause-16         864758560    809567480   -6.81%

ParserLastPause       280537000    289047000   +3.03%
ParserLastPause-2     183030000    166748000   -8.90%
ParserLastPause-4     105817000     91552000  -13.48%
ParserLastPause-8      65127000     53288000  -18.18%
ParserLastPause-16     45258000     38334000  -15.30%

TreeLastPause          45072000     51449000  +12.39%
TreeLastPause-2        39269000     37866000   -3.57%
TreeLastPause-4        23564000     20649000  -12.37%
TreeLastPause-8        20881000     15807000  -24.30%
TreeLastPause-16       23297000     17309000  -25.70%

Tree2LastPause       6046912000   5797120000   -4.13%
Tree2LastPause-2     3724034000   3567592000   -4.20%
Tree2LastPause-4     1874831000   1774524000   -5.65%
Tree2LastPause-8     1363108000   1020809000  -12.79%
Tree2LastPause-16     937208000    767019000  -22.18%

R=rsc, 0xe2.0x9a.0x9b
CC=golang-dev
https://golang.org/cl/6223050

Detect HTML integration points and MathML text integration points.
At these points, process tokens as HTML, not as foreign content.

Pass 33 more tests.

R=nigeltao
CC=golang-dev
https://golang.org/cl/6249044

R=golang-dev, rsc, r
CC=golang-dev
https://golang.org/cl/6250043

R=golang-dev, rsc, devon.odell
CC=golang-dev
https://golang.org/cl/6222044

Import updated test data from the WebKit Subversion repository (SVN revision 118111).

Some of the old tests were failing because we were HTML5 compliant, but the tests weren't.

R=nigeltao
CC=golang-dev
https://golang.org/cl/6228049

Fixes #3650

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6238046

Fixes #3655.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6213065

I needed this to explore per-GOOS/GOARCH differences in pkg
syscall for a recent CL.  Others may find it useful too.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6236046

Fixes #3663
Updates #3540 (fixes it more)
Updates #1967 (fixes it more, re-enables a test)

R=golang-dev, n13m3y3r
CC=golang-dev
https://golang.org/cl/6213064

- there is no label scope at package level
- open/close all scopes symmetrically now
  that there is only one parse entry point
  (parseFile)

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6230047

It's usually due to writing on HEAD requests.

R=golang-dev, rsc, r, r
CC=golang-dev
https://golang.org/cl/6206106

        CL 5823055 removed a line introduced in Linux/ARM cgo support.
        Because readsym() now returns nil for "$a", "$d" mapping symbols,
        no matter the settings of `needSym', we still have to guard against
        them in ldelf().

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6220073

R=rsc
CC=golang-dev
https://golang.org/cl/6225048

This quiets all.bash noise for upcoming features we know about.

The all.bash warnings will now only print for things not in next.txt
(or in next.txt but not in the API).

Once an API is frozen, we rename next.txt to a new frozen file
(like go1.txt)

Fixes #3651

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6218069

Handle text, comment, and doctype tokens in afterBodyIM, afterAfterBodyIM,
and afterAfterFramesetIM.

Pass three more tests.

R=nigeltao
CC=golang-dev
https://golang.org/cl/6231043

Also: simplified some existing tests.

No support for Rats for now because the precision-preserving
default notation (fractions of the form a/b) is not a valid
JSON value.

Fixes #3657.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6211079

Currently, if you pass some data to a template as an interface (e.g. interface{})
and extract that value that value as a parameter for a function, it fails, saying
wrong type.

This is because it is only looking at the interface type, not the interface content.

This CL uses the underlying content as the parameter to the func.

Fixes #3642.

R=golang-dev, r, r
CC=golang-dev
https://golang.org/cl/6218052