Adds parser recovery at the statement level for unterminated statements (no semicolon)

Adds parser recovery at the statement level for unterminated statements (no semicolon)

this change will allow the parser to recover when it sees the start 
of a new statement after an invalid token.  All 24 of these new test 
cases failed in the state the code right before this change, so 
I'm hoping this will make a significant improvement in the quality of 
the AST created and therefore code completion.

Committed: https://code.google.com/p/dart/source/detail?r=6463

[zundel, 2012-04-12 10:35:40]

https://chromiumcodereview.appspot.com/10068008/diff/1/compiler/javatests/com...
File
compiler/javatests/com/google/dart/compiler/parser/TruncatedSourceParserTest.java
(right):

https://chromiumcodereview.appspot.com/10068008/diff/1/compiler/javatests/com...
compiler/javatests/com/google/dart/compiler/parser/TruncatedSourceParserTest.java:25:
private ParseState state = ParseState.INIT;
There are no important changes to this file, but I had to debug what was going
on because there 'testRecoverDirectives' was failing.

[scheglov, 2012-04-12 13:32:50]

LGTM