gpu_test_expectations: Fix test for API overlap

Bug: angleproject:2396
No-Try: True
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I72f61722121e4580b5d24331cf7d19c54f16b396
Reviewed-on: https://chromium-review.googlesource.com/957310
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542256}

gpu/config/gpu_test_config.cc

@@ -147,6 +147,8 @@ bool GPUTestConfig::OverlapsWith(const GPUTestConfig& config) const {
       build_type_ != kBuildTypeUnknown &&
       (build_type_ & config.build_type_) == 0)
     return false;
+  if (config.api() != kAPIUnknown && api_ != kAPIUnknown && api_ != config.api_)
+    return false;
   return true;
 }