CSP: Blocked 'eval()' execution should generate error reports.

Currently, 'eval()' is blocked correctly inside of V8 when a policy is
set that doesn't include 'unsafe-eval' as a source of script. Violation
reports, however, are not sent, as the work is done completely inside of
V8, and never touches the ContentSecurityPolicy implementation in Blink.

This CL hooks into the SetAllowCodeGenerationFromStringsCallback that V8
provides, which allows us to use the same codepath that other eval-like
constructs are running through ('setTimeout()', for example).

This CL only addresses 'Content-Security-Policy'. I believe we'll be
able to support 'Content-Security-Policy-Report-Only' with this
mechanism, but that's left for a future CL.

BUG=248257
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/18988002

git-svn-id: svn://svn.chromium.org/blink/trunk@153994 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Dispose the V8 per isolate data when shutting down WebKit

This mirrors the initialization of the per isolate data when starting
WebKit

BUG=259188
R=mkwst@chromium.org

Review URL: https://codereview.chromium.org/18620005

git-svn-id: svn://svn.chromium.org/blink/trunk@153995 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Disable mouseover preconnect trigger.

The current precision of mouseover trigger is too low to actually trigger preconnects.

BUG=240959

Review URL: https://chromiumcodereview.appspot.com/18893006

git-svn-id: svn://svn.chromium.org/blink/trunk@153996 bbb929c8-8fbe-4397-9dbb-9b2b20218538