The return type of imageSize(gimageCube) is int2, not int3

BUG=angleproject:1442

Change-Id: I18bee163e7c7ce159cd23d6136486c49b7d9ec94
Reviewed-on: https://chromium-review.googlesource.com/414950
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/Initialize.cpp b/src/compiler/translator/Initialize.cpp
index a0b35f6..1dd14b3 100644
--- a/src/compiler/translator/Initialize.cpp
+++ b/src/compiler/translator/Initialize.cpp
@@ -491,7 +491,7 @@
     symbolTable.insertBuiltIn(ESSL3_1_BUILTINS, int2, "imageSize", gimage2D);
     symbolTable.insertBuiltIn(ESSL3_1_BUILTINS, int3, "imageSize", gimage3D);
     symbolTable.insertBuiltIn(ESSL3_1_BUILTINS, int3, "imageSize", gimage2DArray);
-    symbolTable.insertBuiltIn(ESSL3_1_BUILTINS, int3, "imageSize", gimageCube);
+    symbolTable.insertBuiltIn(ESSL3_1_BUILTINS, int2, "imageSize", gimageCube);
 
     //
     // Depth range in window coordinates