Enables AccessibleObjectFromEvent to retrieve the system caret

Each AXPlatformNodeWin, including the accessibility system caret, is assigned a unique ID on construction. Mistakenly, I was assigning a new ID instead of using the existing one when constructing the AXSystemCaretWin object which meant that all events were sent having the wrong object ID.
R=dmazzoni@chromium.org, aleventhal@chromium.org

Bug: 789176
Change-Id: I15681365ad0e461cf29789df9a4f69301e3e6104
Reviewed-on: https://chromium-review.googlesource.com/803858
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521109}
1 file changed