[Command buffer] Enable primitive restart for WebGL 2

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index 143731a384476a021e480090d788dc5dc155f652..37b9117df3e0d902126b9f20e243cf2d6a012b97 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -978,6 +978,12 @@ void WebGLRenderingContextBase::initializeNewContext()
     drawingBuffer()->contextProvider()->setLostContextCallback(WebClosure(WTF::bind(&WebGLRenderingContextBase::forceLostContext, createWeakThisPointer(), WebGLRenderingContextBase::RealLostContext, WebGLRenderingContextBase::Auto)));
     webContext()->setErrorMessageCallback(m_errorMessageCallbackAdapter.get());
 
+    // If WebGL 2, the PRIMITIVE_RESTART_FIXED_INDEX should be always enabled.
+    // See the section <Primitive Restart is Always Enabled> in WebGL 2 spec:
+    // https://www.khronos.org/registry/webgl/specs/latest/2.0/#4.1.4
+    if (isWebGL2OrHigher())
+        contextGL()->Enable(GL_PRIMITIVE_RESTART_FIXED_INDEX);
+
     // This ensures that the context has a valid "lastFlushID" and won't be mistakenly identified as the "least recently used" context.
     contextGL()->Flush();