Get rid of custom code for HTMLDocument.write() / writeln()

Get rid of custom code for HTMLDocument.write() / writeln() by making the
method variadic in Web IDL. Although this is not according to specification,
this matches the behavior of our custom code and the one of FF / IE.

R=haraken
TEST=fast/dom/HTMLDocument/document-write-variadic.html

Review URL: https://codereview.chromium.org/59693007

git-svn-id: svn://svn.chromium.org/blink/trunk@161547 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Cleanup: Combine Worker-specific FileSystem client implementation into the document one

Looks like technically one class can derive from multiple Supplement<T>
(with different T).

This combines WorkerLocalFileSystem into LocalFileSystem, and
WorkerFileSystemClient into LocalFileSystemClient.

BUG=none

Review URL: https://codereview.chromium.org/64293002

git-svn-id: svn://svn.chromium.org/blink/trunk@161548 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move Cookie.h to platform/

BUG=297477

Review URL: https://codereview.chromium.org/59773013

git-svn-id: svn://svn.chromium.org/blink/trunk@161549 bbb929c8-8fbe-4397-9dbb-9b2b20218538