Improve intersection precision in FloatPoint

BUG=314092

Review URL: https://codereview.chromium.org/55263002

git-svn-id: svn://svn.chromium.org/blink/trunk@161214 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix bug in partitionReallocGeneric in the Debug build.

BUG=314025

Review URL: https://codereview.chromium.org/56013007

git-svn-id: svn://svn.chromium.org/blink/trunk@161215 bbb929c8-8fbe-4397-9dbb-9b2b20218538