EnumOrdinalizer cleanup, and fix ICE on empty enums.

- Change to MethodInliner removes spurious casts and the need for special-case
code in EnumOrdinalizer.

- Fix a case in EnumOrdinalizer were we'd try to modify an immutable list of
statements.

- General clean-up of EnumOrdinalizer.

- TypeRemapper correctly records mutations.

- Removed a few of the JavaAstConstructor changes that were put in for
EnumOrdinalizer as they aren't really needed.  What's left is a closer model to
the real java.lang.Enum as it uses native methods.

http://gwt-code-reviews.appspot.com/1426804/
http://gwt-code-reviews.appspot.com/1423809/

Patch by: me, jbrosenberg
Review by: jbrosenberg, me


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10101 8db76d5a-ed1c-0410-87a9-c151d255dfc7