Constraints: Make advanced list be a list.

Constraints: Make advanced list be a list.

Previous behavior: A list of optional constraints resulted
in a single advanced element, with one field for each value.

New behavior: A list of optional constraints results in a
list of advanced elements, with one field set for each value.

The difference is important when there are mulitple values
with the same name. For constraints with distinct names, there
should be no difference.

BUG=594929
Review URL: https://codereview.chromium.org/1808173002

Cr-Commit-Position: refs/heads/master@{#381724}
(cherry picked from commit 20078f72c457d9612c1e12044e7e87fc721b4397)

Conflicts:
	third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp

Committed: https://chromium.googlesource.com/chromium/src/+/557071c271897464f0c1eceb1e8a6590ffb13916

[hta - Chromium, 2016-03-21 08:08:30]

Description was changed from

==========
Constraints: Make advanced list be a list.

Previous behavior: A list of optional constraints resulted
in a single advanced element, with one field for each value.

New behavior: A list of optional constraints results in a
list of advanced elements, with one field set for each value.

The difference is important when there are mulitple values
with the same name. For constraints with distinct names, there
should be no difference.

BUG=594929

Review URL: https://codereview.chromium.org/1808173002

Cr-Commit-Position: refs/heads/master@{#381724}
(cherry picked from commit 20078f72c457d9612c1e12044e7e87fc721b4397)

Conflicts:
	third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp
==========

to

==========
Constraints: Make advanced list be a list.

Previous behavior: A list of optional constraints resulted
in a single advanced element, with one field for each value.

New behavior: A list of optional constraints results in a
list of advanced elements, with one field set for each value.

The difference is important when there are mulitple values
with the same name. For constraints with distinct names, there
should be no difference.

BUG=594929

Review URL: https://codereview.chromium.org/1808173002

Cr-Commit-Position: refs/heads/master@{#381724}
(cherry picked from commit 20078f72c457d9612c1e12044e7e87fc721b4397)

Conflicts:
	third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp

Committed:
https://chromium.googlesource.com/chromium/src/+/557071c271897464f0c1eceb1e8a...
==========

[hta - Chromium, 2016-03-21 08:08:32]

Committed patchset #1 (id:1) manually as
557071c271897464f0c1eceb1e8a6590ffb13916.