Convert fa-history to svg; tweak alignment

app/assets/stylesheets/framework/dropdowns.scss

@@ -97,7 +97,7 @@
   .fa-chevron-down {
     font-size: $dropdown-chevron-size;
     position: relative;
-    top: -3px;
+    top: -2px;
     margin-left: 5px;
   }
 

app/assets/stylesheets/framework/filters.scss

@@ -283,17 +283,10 @@
 .filtered-search-history-dropdown-toggle-button {
   flex: 1;
   width: auto;
-  padding-right: 10px;
-
   border-radius: 0;
-  border-top: 0;
-  border-left: 0;
-  border-bottom: 0;
+  border: 0;
   border-right: 1px solid $border-color;
-
   color: $gl-text-color-secondary;
-  line-height: 1;
-
   transition: color 0.1s linear;
 
   &:hover,
@@ -301,6 +294,17 @@
     color: $gl-text-color;
     border-color: $dropdown-input-focus-border;
     outline: none;
+
+    svg {
+      fill: $gl-text-color;
+    }
+  }
+
+  svg {
+    height: 14px;
+    width: 14px;
+    fill: $gl-text-color-secondary;
+    vertical-align: middle;
   }
 
   .dropdown-toggle-text {
@@ -312,11 +316,6 @@
       color: inherit;
     }
   }
-
-  .fa {
-    position: static;
-  }
-
 }
 
 .filtered-search-history-dropdown {

app/views/shared/icons/_icon_history.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="1792" height="1792" viewBox="0 0 1792 1792"><path d="M1664 896q0 156-61 298t-164 245-245 164-298 61q-172 0-327-72.5T305 1387q-7-10-6.5-22.5t8.5-20.5l137-138q10-9 25-9 16 2 23 12 73 95 179 147t225 52q104 0 198.5-40.5T1258 1258t109.5-163.5T1408 896t-40.5-198.5T1258 534t-163.5-109.5T896 384q-98 0-188 35.5T548 521l137 138q31 30 14 69-17 40-59 40H192q-26 0-45-19t-19-45V256q0-42 40-59 39-17 69 14l130 129q107-101 244.5-156.5T896 128q156 0 298 61t245 164 164 245 61 298zm-640-288v448q0 14-9 23t-23 9H672q-14 0-23-9t-9-23v-64q0-14 9-23t23-9h224V608q0-14 9-23t23-9h64q14 0 23 9t9 23z"/></svg>

app/views/shared/issuable/_search_bar.html.haml

@@ -13,7 +13,7 @@
       .issues-other-filters.filtered-search-wrapper
         .filtered-search-box
           - if type != :boards_modal && type != :boards
-            = dropdown_tag(content_tag(:i, '', class: 'fa fa-history'),
+            = dropdown_tag(custom_icon('icon_history'),
               options: { wrapper_class: "filtered-search-history-dropdown-wrapper",
               toggle_class: "filtered-search-history-dropdown-toggle-button",
               dropdown_class: "filtered-search-history-dropdown",