1. Select-to-speak needs to ignore nodes with an 'invisible' state, this will keep it from reading other options when <select> is not expanded.

2. Select drop-downs don't update node states to remove 'invisible' when expanded. Except, after ChromeVox reads a <option>, it is updated properly. Updating 'invisible' will let it read other options when <select> is expanded.

3. Select drop-downs don't seem to have location for children in popup menu. This will make it hard to read individual pop-up menu elements. That seems lower priority.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a2d045d7940f9604560c798539a5ea3f05f0471e

commit a2d045d7940f9604560c798539a5ea3f05f0471e
Author: Katie Dektar <katydek@google.com>
Date: Wed Nov 15 01:39:42 2017

Opening and closing select tag updates children state.

Previously, the 'invisible' tag was not removed from <select>
popup's children elements even when the <select> was expanded. This
change causes all children of a <select> popup to be updated when
the popup is opened or closed.

In addition, the change causes Select-to-speak will ignore
'invisible' nodes. See go/chrome-a11y-offscreen-invisible for more.

With these two changes combined now Select-to-speak will not read
aloud all the options in a closed combobox, but will still read
them all if that combo box is expanded.

Bug:  777059 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I2424fdf04248b7b91c607388376ee957beea8e06
Reviewed-on: https://chromium-review.googlesource.com/769674
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Katie D <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516549}
[modify] https://crrev.com/a2d045d7940f9604560c798539a5ea3f05f0471e/chrome/browser/resources/chromeos/select_to_speak/select_to_speak.js
[modify] https://crrev.com/a2d045d7940f9604560c798539a5ea3f05f0471e/content/renderer/accessibility/render_accessibility_impl.cc
[modify] https://crrev.com/a2d045d7940f9604560c798539a5ea3f05f0471e/third_party/WebKit/Source/modules/accessibility/AXMenuListPopup.cpp

I'm going to mark this as fixed, and open a separate bug for #3.

To verify, make sure that:
1. Select-to-speak only reads the selected option when the combobox is closed
2. When the combobox is expanded, and the user highlights the combobox itself (not the popup menu), all the options should be read.
3. After closing the combobox again, only the selected option should be read.

Moving from just having STS label to also having the UI>Accessibility>SelectToSpeak component to make searching easier in the future.