Mac: Include Radeon 4670 in overlay blacklist

Reports indicate that this card is affected as well.

TBR=zmo
BUG=543324

Review URL: https://codereview.chromium.org/1469933004

Cr-Commit-Position: refs/heads/master@{#361263}

gpu/config/gpu_driver_bug_list_json.cc

@@ -1591,7 +1591,7 @@ LONG_STRING_CONST(
         "type": "macosx"
       },
       "vendor_id": "0x1002",
-      "device_id": ["0x9440", "0x944a"],
+      "device_id": ["0x9440", "0x944a", "0x9488", "0x9490"],
       "features": [
         "disable_overlay_ca_layers",
         "disable_post_sub_buffers_for_onscreen_surfaces"