9b0697baac
To use in the inline local refactoring. 1. We can unwrap a literal only if its `isSingleQuoted` is the same as of the target literal. 2. We can unwrap a single-line literal into a multi-line one, but not vice versa. R=brianwilkerson@google.com, paulberry@google.com BUG= Review URL: https://codereview.chromium.org//632203002 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@40957 260f80e4-7a28-3924-810f-c04153c831b5