Fix a compilation error for the ES3 CTS in 64bit.

The generated obj file was too large, it required an extra MSVC flag for
this particular project.

BUG=angle:497

Change-Id: I833a78611da78b0ac5a308547d11a911428ea04c
Reviewed-on: https://chromium-review.googlesource.com/214684
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/tests/tests.gyp b/tests/tests.gyp
index 922e149..ee6d696 100644
--- a/tests/tests.gyp
+++ b/tests/tests.gyp
@@ -294,6 +294,14 @@
                             [
                                 'CONFORMANCE_TESTS_TYPE=CONFORMANCE_TESTS_ES3',
                             ],
+                            'msvs_settings':
+                            {
+                                'VCCLCompilerTool':
+                                {
+                                    # MSVS has trouble compiling this due to the obj files becoming too large.
+                                    'AdditionalOptions': [ '/bigobj' ],
+                                },
+                            },
                             'actions':
                             [
                                 {