fix: script tag - unhandled exception in case of absolute path in "src" attribute

+ some unit tests
removed deprecated function literal
response to comments by sigmundch

see https://github.com/dart-lang/web-ui/pull/265
refactoring: removed global 'messages' in 'messages.dart'
simplified test expressions
reusing mock 'messages'
Fix #269 - detect correctly generated files that are indirectly under the out
folder.

Review URL: https://chromiumcodereview.appspot.com//11611003
Update CHANGELOG.md
Merge pull request #265 from Gubaer/fix-absolute-path-in-script-src-attribute

fix: script tag - unhandled exception in case of absolute path in "src" ...
Update CHANGELOG.md
Improvements for run.sh and run_all.dart:
 * introduces a configuration that prints status on every test, and rewrites the
   same line when everything is OK. When running locally, the status line is
   updated in place. In drone, a separate line is printed, so we don't lose any
   information there (see https://drone.io/dart-lang/web-ui/73)

 * this change also runs DumpRenderTree from dart. On a successful
   run we only see 1 line for all these tests.

The interactive mode for updating expectations is still done in bash, also the
analyzer is still run separately as we do today.

Review URL: https://chromiumcodereview.appspot.com//11623003
Merge branch 'master' into fix-global-messages
reponse to comments by jmesserly

see https://github.com/dart-lang/web-ui/issues/267#issuecomment-11515728
Merge pull request #271 from Gubaer/fix-global-messages

Fix global messages
added support for optional 'baseDir' argment in build.dart

I need this for my project where I set --basedir . in order to use
components in lib/ in my example/example.html
Revert "added support for optional 'baseDir' argment in build.dart"

This reverts commit eeb0ae7bde8445ce4306eccf34168b24c0c0631c.
added suport for optional 'baseDir' argument in build.dart
Revert "added suport for optional 'baseDir' argument in build.dart"

This reverts commit a9a0c7e2193705eca525a73479d8d4f8c63c1c2c.
added support for optional 'baseDir' argument to component_build
Revert "added support for optional 'baseDir' argument to component_build"

This reverts commit 42f11b0d404b79d8d3fc5e8a582b5c1f0eb3c509.