Always use TFunction instead of TFunctionSymbolInfo

This reduces unnecessary memory allocations and conversions between
different objects containing the same data.

BUG=angleproject:2267
TEST=angle_unittests

Change-Id: I87316509ab1cd6d36756ff6af7fa2b5c5a76a8ea
Reviewed-on: https://chromium-review.googlesource.com/827134
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/IntermTraverse.cpp b/src/compiler/translator/IntermTraverse.cpp
index 5c23e6d..8c45d75 100644
--- a/src/compiler/translator/IntermTraverse.cpp
+++ b/src/compiler/translator/IntermTraverse.cpp
@@ -675,7 +675,7 @@
 void TLValueTrackingTraverser::traverseFunctionPrototype(TIntermFunctionPrototype *node)
 {
     TIntermSequence *sequence = node->getSequence();
-    addToFunctionMap(node->getFunctionSymbolInfo()->getId(), sequence);
+    addToFunctionMap(node->getFunction()->uniqueId(), sequence);
 
     TIntermTraverser::traverseFunctionPrototype(node);
 }