Adds support for POST request with bodies on WKWebView.

Adds support for POST request with bodies on WKWebView.

These requests are now handled through a javascript hack to work around
this webkit bug: https://bugs.webkit.org/show_bug.cgi?id=145410.

BUG=489692
Review URL: https://codereview.chromium.org/1375023002

Cr-Commit-Position: refs/heads/master@{#363256}
(cherry picked from commit 8d13d52f53c03f6b78ab8fbf7148155780063244)

Committed: https://chromium.googlesource.com/chromium/src/+/b35e6bfd6a0ed765ab02746c7fa5978a3009e01c

[lpromero, 2015-12-11 12:49:37]

Description was changed from

==========
Adds support for POST request with bodies on WKWebView.

These requests are now handled through a javascript hack to work around
this webkit bug: https://bugs.webkit.org/show_bug.cgi?id=145410.

BUG=489692

Review URL: https://codereview.chromium.org/1375023002

Cr-Commit-Position: refs/heads/master@{#363256}
(cherry picked from commit 8d13d52f53c03f6b78ab8fbf7148155780063244)
==========

to

==========
Adds support for POST request with bodies on WKWebView.

These requests are now handled through a javascript hack to work around
this webkit bug: https://bugs.webkit.org/show_bug.cgi?id=145410.

BUG=489692

Review URL: https://codereview.chromium.org/1375023002

Cr-Commit-Position: refs/heads/master@{#363256}
(cherry picked from commit 8d13d52f53c03f6b78ab8fbf7148155780063244)

Committed:
https://chromium.googlesource.com/chromium/src/+/b35e6bfd6a0ed765ab02746c7fa5...
==========

[lpromero, 2015-12-11 12:49:38]

Committed patchset #1 (id:1) manually as
b35e6bfd6a0ed765ab02746c7fa5978a3009e01c.