Move DocumentFragment construction in Pasteboard to Editor.

This DOM knowledge does not belong in core/platform/.

BUG=276565

Review URL: https://codereview.chromium.org/22981006

git-svn-id: svn://svn.chromium.org/blink/trunk@159507 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use icu::BreakIterator instead of the ubrk_* api. It makes the code cleaner.

BUG=232922

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=159441

Review URL: https://codereview.chromium.org/23618052

git-svn-id: svn://svn.chromium.org/blink/trunk@159508 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Don't show entries of loading Blob URL from FileReaderLoader

When using FileReaderLoader, Blob URL resource appears on the Inspector
Network Panel since FileReaderLoader uses ThreadableLoader internally.
Not to show that, we introduce "internal" new initiator type.
When it is set, the Inspector ignores this request.

BUG=288658

Review URL: https://codereview.chromium.org/24146006

git-svn-id: svn://svn.chromium.org/blink/trunk@159509 bbb929c8-8fbe-4397-9dbb-9b2b20218538