Make blit extension check for internal format mismatch.

The extension spec dictates a format mismatch generates invalid
operation. Since we can't have the same internal format map to
different actual/native formats, this check is more strict and
we can replace the previous one.

BUG=angle:769

Change-Id: Ic1b5c335ba38a4f2feaffa1478a65e7fcf7f75ea
Reviewed-on: https://chromium-review.googlesource.com/221065
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libGLESv2/validationES.cpp b/src/libGLESv2/validationES.cpp
index 38c8c5e..59c18a2 100644
--- a/src/libGLESv2/validationES.cpp
+++ b/src/libGLESv2/validationES.cpp
@@ -588,7 +588,8 @@
                             return false;
                         }
 
-                        if (attachment->getActualFormat() != readColorBuffer->getActualFormat())
+                        // Return an error if the destination formats do not match
+                        if (attachment->getInternalFormat() != readColorBuffer->getInternalFormat())
                         {
                             context->recordError(Error(GL_INVALID_OPERATION));
                             return false;