Import 4 GWT changes from Gerrit (gerrit/google/pu: 47d58530).

Full changelog for this import:
https://gwt.googlesource.com/gwt/+log/e5d22e80..47d58530

47d5853 mdempsky@google.com Merge branch 'master' into google/pu
3eb6a30 skybrian@google.com Merge "Allow GWT to continue even in presence of internal JDT compiler Errors."
52549a6 gryder@google.com Adds a SafeUri overload to AnchorElement.setHref().
4747eaa rluble@google.com Allow GWT to continue even in presence of internal JDT compiler Errors.