Emit a warning if (some) incompatible options are used.

In particular when -XenableClosureCompiler is used story of your compile reports
are disabled.

The GWT compiler does not keep track of the optimnization performed by the
Closure compiler, hence it lacks the information to produce a report that matches the
output.

Fixes issue 7475

Change-Id: I0e73b0107c23e54b69b9e648bff05d2135ff0b77
Review-Link: https://gwt-review.googlesource.com/#/c/1760/

Review by: skybrian@google.com
Currently the GWT compiler adds a var declaration for each catch parameter in
a try/catch statement, but this is unneeded according to the spec, and the
Closure compiler will issue errors against it.

Change-Id: I05dd0429ec22315d57069046b0139ecce045919e
Review-Link: https://gwt-review.googlesource.com/#/c/1810/
Fixes internal compiler error caused by a null logger parsing jsni code that was generated by a generator at test time.

Change-Id: I034918d940c3318bc82ed9cb615c6f64b89fb027
Review-Link: https://gwt-review.googlesource.com/#/c/1830/

Review by: skybrian@google.com
Shard UiSuite to make the smoke tests faster.

Change-Id: I235b097f19cbcb46fae16515128de0a07c32270b
Review-Link: https://gwt-review.googlesource.com/#/c/1821/