Compiler does not validate state name metadata on skinnable components

Steps to reproduce:
1. Create a skinnable component with state
[SkinState("0")]
2. Instantiate it in an application and compile
3. Create a skin for the skinnable component, with the skin state "0"
4. Apply it to the instance from step 2
5. Compile

(Attached .fxp has these files)

Actual Results:
Compiles at step 2
Compiler error at step 5

Expected Results:
Compiler error at step 2 and 5
Skinnable components should have their skin state metadata validated, because we will never be able to create a valid skin for a component with bad state names. If the skin is auto-generated with these state names (as in Catalyst), then it will cause compile errors.

Workaround (if any):
Rename your states