Speculative crash fix on Document::haveImportsLoaded()

This adds some extra guard for clearing Document::m_import
in case an imported ocuement outlives HTMLImportChild and
also attempts to prevent the outlive by canceling the parser.

The change on Document::haveImportsLoaded() was made
so that the crash report can possibly show precise crashing statement.

TEST=none
R=tkent@chromium.org, dominicc@chromium.org
BUG=358618

Review URL: https://codereview.chromium.org/226173003

git-svn-id: svn://svn.chromium.org/blink/trunk@170980 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: remove CSSRule.sourceURL from protocol.json

This patch removes CSSRule.sourceURL from protocol.json as this
information could be retrieved through parent style sheet.

BUG=341506

Review URL: https://codereview.chromium.org/224903019

git-svn-id: svn://svn.chromium.org/blink/trunk@170981 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Measure usage for Element method webkitRequestPointerLock.

BUG=359747

Review URL: https://codereview.chromium.org/216883011

git-svn-id: svn://svn.chromium.org/blink/trunk@170982 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Blink side changes to removing WebFrame parameter from WebPermissionClient, since it's redundant now.

BUG=304341

Review URL: https://codereview.chromium.org/225303007

git-svn-id: svn://svn.chromium.org/blink/trunk@170983 bbb929c8-8fbe-4397-9dbb-9b2b20218538