parsing input type=number should skip spaces
skipping spaces in number string parsing without reformatting user input.

BUG=162463

Review URL: https://codereview.chromium.org/235273003

git-svn-id: svn://svn.chromium.org/blink/trunk@171834 bbb929c8-8fbe-4397-9dbb-9b2b20218538