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This change implements automatic reading behavior for the ChromeVox
tutorial. This change implements the following:

1. When an interactive lesson is shown, read the lesson title. This
is needed because we focus the text content for these lessons.
2. When a non-interactive lesson is shown, read the lesson contents.
3. Refactor requestSpeech() to pass queuemode and properties
for more control over speech behavior.
4. Add @suppresss statements to a few functions. This allows
us to reference the panel window without triggering closure errors.

Automated tests are included confirm bullets 1 and 2.

Fixed: 1129194
Change-Id: I2ce38fc0228bce749033f4effac4b79846dd696f
AX-Relnotes: N/A
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2414776
Commit-Queue: Akihiro Ota <akihiroota@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812503}