Expand ShShaderOutput for different GLSL versions

BUG=angleproject:968

Change-Id: I2d4c0a8e9a91a940922da4501c22124da0c0399c
Reviewed-on: https://chromium-review.googlesource.com/264840
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/Compiler.h b/src/compiler/translator/Compiler.h
index eda856b..e2cb58e 100644
--- a/src/compiler/translator/Compiler.h
+++ b/src/compiler/translator/Compiler.h
@@ -37,6 +37,11 @@
 bool IsWebGLBasedSpec(ShShaderSpec spec);
 
 //
+// Helper function to check if the shader type is GLSL.
+//
+bool IsGLSL130OrNewer(ShShaderOutput output);
+
+//
 // The base class used to back handles returned to the driver.
 //
 class TShHandleBase {