Bug 1157898 part 1. Make code of the form "return rv.ErrorCode();" where rv is an ErrorResult use StealNSResult instead. r=peterv

This patch was generated with the following command:

  find . -name "*.h" -o -name "*.cpp" | xargs perl -pi -e 's/return ([a-zA-Z0-9]+)\.ErrorCode\(\);/return \1.StealNSResult();/'

dom/html/HTMLFrameSetElement.cpp

@@ -33,7 +33,7 @@ HTMLFrameSetElement::SetCols(const nsAString& aCols)
 {
   ErrorResult rv;
   SetCols(aCols, rv);
-  return rv.ErrorCode();
+  return rv.StealNSResult();
 }
 
 NS_IMETHODIMP
@@ -50,7 +50,7 @@ HTMLFrameSetElement::SetRows(const nsAString& aRows)
 {
   ErrorResult rv;
   SetRows(aRows, rv);
-  return rv.ErrorCode();
+  return rv.StealNSResult();
 }
 
 NS_IMETHODIMP