don't write empty run(in Excel empty run is editable and has size).Write only...

don't write empty run(in Excel empty run is editable and has size).Write only if it is single single in Content

word/Editor/Serialize2.js

@@ -2349,7 +2349,7 @@ function Binary_oMathWriter(memory, oMathPara, saveParams)
     this.bs = new BinaryCommonWriter(this.memory);
 	this.brPrs = new Binary_rPrWriter(this.memory, saveParams);
 	
-	this.WriteMathElem = function(item)
+	this.WriteMathElem = function(item, isSingle)
 	{
 		var oThis = this;
 		switch ( item.Type )
@@ -2379,7 +2379,7 @@ function Binary_oMathWriter(memory, oMathPara, saveParams)
 						case "OMath"			: this.bs.WriteItem(c_oSer_OMathContentType.OMath, function(){oThis.WriteArgNodes(item);});			break;
 						case "OMathPara"		: this.bs.WriteItem(c_oSer_OMathContentType.OMathPara, function(){oThis.WriteOMathPara(item);});break;
 						case MATH_PHANTOM		: this.bs.WriteItem(c_oSer_OMathContentType.Phant, function(){oThis.WritePhant(item);});		break;
-						case MATH_RUN			: this.bs.WriteItem(c_oSer_OMathContentType.MRun, function(){oThis.WriteMRun(item);});			break;
+						case MATH_RUN			: this.WriteMRunWrap(item, isSingle);break;
 						case MATH_RADICAL		: this.bs.WriteItem(c_oSer_OMathContentType.Rad, function(){oThis.WriteRad(item);});			break;
 						case MATH_DEGREESubSup	: 
 							if (DEGREE_PreSubSup == item.Pr.type)
@@ -2401,7 +2401,7 @@ function Binary_oMathWriter(memory, oMathPara, saveParams)
 				this.bs.WriteItem(c_oSer_OMathContentType.MText, function(){ oThis.memory.WriteString2(AscCommon.convertUnicodeToUTF16([item.value]));}); //m:t
 				break;
 			case para_Math_Run:
-				this.bs.WriteItem(c_oSer_OMathContentType.MRun, function(){oThis.WriteMRun(item);});
+				this.WriteMRunWrap(item, isSingle);
 				break;
 			default:		
 				break;
@@ -2419,15 +2419,24 @@ function Binary_oMathWriter(memory, oMathPara, saveParams)
 			if (argSz)
 				this.bs.WriteItem(c_oSer_OMathContentType.ArgPr, function(){oThis.WriteArgPr(argSz);});
 			
-
+			var isSingle = (nStart === nEnd - 1);
 			for(var i = nStart; i <= nEnd - 1; i++)
 			{
 				var item = oElem.Content[i];
-				this.WriteMathElem(item);
+				this.WriteMathElem(item, isSingle);
 			}
 		}
 		
 	}
+	this.WriteMRunWrap = function(oMRun, isSingle)
+	{
+		var oThis = this;
+		if (!isSingle && oMRun.Is_Empty()) {
+			//don't write empty run(in Excel empty run is editable and has size).Write only if it is single single in Content
+			return;
+		}
+		this.bs.WriteItem(c_oSer_OMathContentType.MRun, function(){oThis.WriteMRun(oMRun);});
+	}
 	this.WriteMRun = function(oMRun)
 	{
 		var oThis = this;