Reorganize clearing methods in XMLHttpRequest

m_receivedLength, m_decoder and m_responseEncoding are not used once loading
is finished. Group them and reset in a method named clearVariablesForLoading.

Add some comments about response holder variables.

Some code reorg for readability in didReceiveData().

BUG=

Review URL: https://codereview.chromium.org/25472002

git-svn-id: svn://svn.chromium.org/blink/trunk@158623 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove an unnecessary WebSocket constructor.

Also clean up some unnecessary prefixes.

Review URL: https://codereview.chromium.org/25444002

git-svn-id: svn://svn.chromium.org/blink/trunk@158624 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Empty @viewport should not override legacy viewport.

@viewport styles should not be considered present in author styles if there is
not a single descriptor present. This is not specified anywhere, though.

Marking the ViewportStyleResolver with author styles present when there were
no descriptors caused an assert to trigger (see mentioned BUG). This is fixed
by always require at least one descriptor to be present in order to set the
flag for author style presence, keeping the assert.

As part of this fix, collectViewportRules was refactored into
ViewportStyleResolver to resolve a FIXME in the StyleResolver.

BUG=299719

Review URL: https://codereview.chromium.org/25257003

git-svn-id: svn://svn.chromium.org/blink/trunk@158625 bbb929c8-8fbe-4397-9dbb-9b2b20218538