r177180 - Refactor template diffing to store an enum that records which type of

[David Blaikie]

> @@ -1134,30 +1131,32 @@ class TemplateDiff {
>
>      // Handle cases where the difference is not templates with different
>      // arguments.
> -    if (!Tree.NodeIsTemplate()) {
> -      if (Tree.NodeIsQualType()) {
> +    switch (Tree.GetKind()) {
> +      default:

This default breaks the Clang -Werror build due to
-Wcovered-switch-default. I've removed it in r177184 to get the build
green again.

- David