[WebGL 2] primitive restart should be always enabled

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 daa0ac8ad797dc7c1b37fce5fd48bd6ba22da8ce..c392b3913cc30ff63080f2acd46a542361769d79 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -987,6 +987,12 @@ void WebGLRenderingContextBase::initializeNewContext()
     webContext()->setContextLostCallback(m_contextLostCallbackAdapter.get());
     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())
+        webContext()->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.
     webContext()->flush();