Fix linkage.html failures on Mac.

The failure is due to when we initialize variables to 0, we re-create
the struct TType, and it contains a different unique id from the
original struct TType, thus leading to a different hashed name.

BUG=chromium:641129
TEST=webgl_conformance,webgl2_conformance

Change-Id: I267b97fa496f55ea59dacee93af8f6a90f3e66cb
Reviewed-on: https://chromium-review.googlesource.com/409602
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/SymbolTable.h b/src/compiler/translator/SymbolTable.h
index 439d6b4..7c4d3aa 100644
--- a/src/compiler/translator/SymbolTable.h
+++ b/src/compiler/translator/SymbolTable.h
@@ -459,8 +459,11 @@
 
     TSymbol *find(const TString &name, int shaderVersion,
                   bool *builtIn = NULL, bool *sameScope = NULL) const;
+
+    TSymbol *findGlobal(const TString &name) const;
+
     TSymbol *findBuiltIn(const TString &name, int shaderVersion) const;
-    
+
     TSymbolTableLevel *getOuterLevel()
     {
         assert(currentLevel() >= 1);