Implement primitive restart boolean query.

We have support for primitive restart in the GL renderer, but we
didn't complete support for the state query.

BUG=angleproject:1101

Change-Id: I4c6ad10642f7de1d09718c4582f1037782cced58
Reviewed-on: https://chromium-review.googlesource.com/309151
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@google.com>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/State.cpp b/src/libANGLE/State.cpp
index 32112a8..e9e96a2 100644
--- a/src/libANGLE/State.cpp
+++ b/src/libANGLE/State.cpp
@@ -1265,6 +1265,9 @@
       case GL_DITHER:                    *params = mBlend.dither;                 break;
       case GL_TRANSFORM_FEEDBACK_ACTIVE: *params = getCurrentTransformFeedback()->isActive() ? GL_TRUE : GL_FALSE; break;
       case GL_TRANSFORM_FEEDBACK_PAUSED: *params = getCurrentTransformFeedback()->isPaused() ? GL_TRUE : GL_FALSE; break;
+      case GL_PRIMITIVE_RESTART_FIXED_INDEX:
+          *params = mPrimitiveRestart;
+          break;
       default:
         UNREACHABLE();
         break;