Revert "Implement gl_FragDepth for GLES SL 3.0"

assertion failures in WebGL2 CTS.

This reverts commit 544809610a131fe7040f2212789c62e212bbaf24.

Change-Id: I2e0c7045c5b6ef9031a6e6c5916504fe68f51077
Reviewed-on: https://chromium-review.googlesource.com/287910
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/compiler/translator/OutputHLSL.cpp b/src/compiler/translator/OutputHLSL.cpp
index cfdd280..e094db2 100644
--- a/src/compiler/translator/OutputHLSL.cpp
+++ b/src/compiler/translator/OutputHLSL.cpp
@@ -1386,7 +1386,7 @@
             mUsesInstanceID = true;
             out << name;
         }
-        else if (name == "gl_FragDepthEXT" || name == "gl_FragDepth")
+        else if (name == "gl_FragDepthEXT")
         {
             mUsesFragDepth = true;
             out << "gl_Depth";