INPUT/TEXTAREA elements: Fix incorrect selectionStart/selectionEnd values after blur.
We failed to update selectionStart/selectionEnd cache because
TextControlElement::SelectionChanged() is not called in some cases after
crrev.com/450370.
After this CL, selection values are cached in webkitEditableContentChanged event
handling code too. It is called on every DOM mutation in text control editor.
BUG=714425
Review-Url: https://codereview.chromium.org/2878613002
Cr-Commit-Position: refs/heads/master@{#471290}
3 files changed
