Better error message for 'catch' block missing 'try'.

[DanielRosenwasser]

Consider the following source file:

catch (x) {
}

Currently the compiler reports these errors:

(1,2): Declaration or statement expected.
(1,12): ';' expected.                    

And if we merge 57d7cf5, the compiler will report

(1,1): Declaration or statement expected.
(1,11): '=>' expected.                   

We should give better errors for catch blocks missing try blocks.