Add Math.cbrt, improve Math.log10, add tests.

Public review: http://gwt-code-reviews.appspot.com/150803/show

Issue: 4308, 4637
Patch by: jat, elk
Review by: jlabanca


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@7605 8db76d5a-ed1c-0410-87a9-c151d255dfc7
3 files changed