Added support for EXT_frag_depth

This change also required that support be added for associating built-in
variables with an extension, similar to how functions could be associated with
extensions previously.

R=alokp@chromium.org

Review URL: https://codereview.appspot.com/9827044

git-svn-id: https://angleproject.googlecode.com/svn/trunk@2248 736b8ea6-26fd-11df-bfd4-992fa37f6226

TRAC #23333
Authored-by: bajones@chromium.org
Signed-off-by: Shannon Woods
Signed-off-by Nicolas Capens
Merged-by: Jamie Madill
diff --git a/src/compiler/ParseHelper.h b/src/compiler/ParseHelper.h
index 139b8f8..febdc1b 100644
--- a/src/compiler/ParseHelper.h
+++ b/src/compiler/ParseHelper.h
@@ -117,6 +117,7 @@
     bool containsSampler(TType& type);
     bool areAllChildConst(TIntermAggregate* aggrNode);
     const TFunction* findFunction(const TSourceLoc& line, TFunction* pfnCall, int shaderVersion, bool *builtIn = 0);
+    bool isVariableBuiltIn(const TVariable* var);
     bool executeInitializer(const TSourceLoc& line, const TString& identifier, TPublicType& pType,
                             TIntermTyped* initializer, TIntermNode*& intermNode, TVariable* variable = 0);