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/OutputGLSL.cpp b/src/compiler/OutputGLSL.cpp
index 206f403..10a451c 100644
--- a/src/compiler/OutputGLSL.cpp
+++ b/src/compiler/OutputGLSL.cpp
@@ -19,3 +19,17 @@
 {
     return false;
 }
+
+void TOutputGLSL::visitSymbol(TIntermSymbol* node)
+{
+    TInfoSinkBase& out = objSink();
+
+    if (node->getSymbol() == "gl_FragDepthEXT")
+    {
+        out << "gl_FragDepth";
+    }
+    else
+    {
+        TOutputGLSLBase::visitSymbol(node);
+    }
+}