The link shoud be activated by enter key on focusing the child element inside the anchor.
This makes behaviour consistent with firefox and IE.

BUG=350738
R=pdr@chromium.org
R=rob@robwu.nl
TEST=LayoutTests/fast/events/keydown-enter-key-on-focused-element-inside-link.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184074

Review URL: https://codereview.chromium.org/619613005

git-svn-id: svn://svn.chromium.org/blink/trunk@184411 bbb929c8-8fbe-4397-9dbb-9b2b20218538