Bug 1466168: Remove mozilla::Forward in favor of std::forward. r=froydnj

Same approach as the other bug, mostly replacing automatically by removing
'using mozilla::Forward;' and then:

  s/mozilla::Forward/std::forward/
  s/Forward</std::forward</

The only file that required manual fixup was TestTreeTraversal.cpp, which had
a class called TestNodeForward with template parameters :)

MozReview-Commit-ID: A88qFG5AccP

image/DecoderFactory.cpp

@@ -310,7 +310,7 @@ DecoderFactory::CreateDecoderForICOResource(DecoderType aType,
 
   // Initialize the decoder, copying settings from @aICODecoder.
   decoder->SetMetadataDecode(aIsMetadataDecode);
-  decoder->SetIterator(Forward<SourceBufferIterator>(aIterator));
+  decoder->SetIterator(std::forward<SourceBufferIterator>(aIterator));
   if (!aIsMetadataDecode) {
     decoder->SetOutputSize(aICODecoder->OutputSize());
   }