Fix SharedWorker leak when script load has failed.

When SharedWorker script load has failed and the |WebSharedWorkerImpl|
was explicit told to terminate, the |WebSharedWorkerImpl| instance
was never deleted.

This CL fixes the issue by invoking "delete this" when a worker thread
instance does not exist in |stopWorkerThread()|.

TEST=fast/workers/worker-crash-with-invalid-location.html doesn't leak when --enable-leak-detection
BUG=364390

Review URL: https://codereview.chromium.org/424653002

git-svn-id: svn://svn.chromium.org/blink/trunk@179011 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Decouple CSS model from UI entities

CSSPresentationModel has been introduced in order to
- manage source mappings,
- store live locations,
- perform the rawLocationToUILocation conversions.

R=pfeldman, vsevik

Review URL: https://codereview.chromium.org/297923002

git-svn-id: svn://svn.chromium.org/blink/trunk@179012 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Network Panel: remove a bit of css poison.

* selector is not required.

BUG=316092

Review URL: https://codereview.chromium.org/420193004

git-svn-id: svn://svn.chromium.org/blink/trunk@179013 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Do not focus navigator on sources panel by default.

R=apavlov

Review URL: https://codereview.chromium.org/426563004

git-svn-id: svn://svn.chromium.org/blink/trunk@179014 bbb929c8-8fbe-4397-9dbb-9b2b20218538