add dox to SkTDynamicHash, fix typo of Key instead of KEY

BUG=
R=mtklein@google.com

Review URL: https://codereview.chromium.org/21028008

git-svn-id: http://skia.googlecode.com/svn/trunk@10465 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed