ImageCapture: don't list |torch| in Capabilities if not supported

ImageCapture: don't list |torch| in Capabilities if not supported

Currently MediaStreamTrack.getCapabilities() returns
 torch : false

when |torch| is not supported; this CL aligns with the
other dictionary members behaviour, which is to not
show up in the Capabilities dictionary when not supported.

BUG=712719
Review-Url: https://codereview.chromium.org/2827693003
Cr-Commit-Position: refs/heads/master@{#465373}
(cherry picked from commit 31b31da235decd6c593745e98f77b55ff9270cb4)

Review-Url: https://codereview.chromium.org/2830943002 .
Cr-Commit-Position: refs/branch-heads/3071@{#69}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/89bfdc09da805adc9bb85bfcb4e38e62bb3d2833

[mcasas, 2017-04-19 22:33:10]

Description was changed from

==========
ImageCapture: don't list |torch| in Capabilities if not supported

Currently MediaStreamTrack.getCapabilities() returns
 torch : false

when |torch| is not supported; this CL aligns with the
other dictionary members behaviour, which is to not
show up in the Capabilities dictionary when not supported.

BUG=712719

Review-Url: https://codereview.chromium.org/2827693003
Cr-Commit-Position: refs/heads/master@{#465373}
(cherry picked from commit 31b31da235decd6c593745e98f77b55ff9270cb4)
==========

to

==========
ImageCapture: don't list |torch| in Capabilities if not supported

Currently MediaStreamTrack.getCapabilities() returns
 torch : false

when |torch| is not supported; this CL aligns with the
other dictionary members behaviour, which is to not
show up in the Capabilities dictionary when not supported.

BUG=712719

Review-Url: https://codereview.chromium.org/2827693003
Cr-Commit-Position: refs/heads/master@{#465373}
(cherry picked from commit 31b31da235decd6c593745e98f77b55ff9270cb4)

Review-Url: https://codereview.chromium.org/2830943002 .
Cr-Commit-Position: refs/branch-heads/3071@{#69}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/89bfdc09da805adc9bb85bfcb4e3...
==========

[mcasas, 2017-04-19 22:33:11]

Committed patchset #1 (id:1) manually as
89bfdc09da805adc9bb85bfcb4e38e62bb3d2833.