webgl.js: Fix so that all calls to checkInstancedVertexAttribState

uses the correct arguments.

With that, all tests cases pass again.

webgl.js

@@ -747,7 +747,7 @@ function createANGLEInstancedArrays (context) {
     if (count > 0) {
       maxIndex = (count + first - 1) >>> 0
     }
-    if (checkInstancedVertexAttribState(maxIndex, primCount)) {
+    if (checkInstancedVertexAttribState(context, maxIndex, primCount)) {
       return _drawArraysInstanced.call(
         context, mode, first, reducedCount, primCount)
     }