Direct doDefault actions to parents of inlineTextBox nodes.
Performing a doDefault action on an inlineTextBox currently fails because within Blink, the associated WebAxObject has no corresponding action element.
Make the fix in ChromeVox. We should consider moving this up to either the Automation API or directly into Blink itself.
TEST=doDefault() on an inline textbox descendant of a link. Observe page transition.
Review URL: https://codereview.chromium.org/
1131293003
Cr-Commit-Position: refs/heads/master@{#328998}