IndexedDB: Make sure indexing completes if object store is deleted

Unhandled case found via W3c web-platform-tests. If an indexing
operation is kicked off then the object store is deleted, an
ASSERT was hit since the cursor is invalid. Check (via the cursor)
that the store has not been deleted; if it has, stop indexing.

BUG=362711

Review URL: https://codereview.chromium.org/235883002

git-svn-id: svn://svn.chromium.org/blink/trunk@171377 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[CSS Shapes] shape-margin in percentage units always computes to 0px

Make shape-margin parsing accept percentages and properly compute the
length once the percentage is accepted.

This is a merge of http://trac.webkit.org/changeset/166787 by Bem Jones-Bey <bjonesbe@adobe.com>.

BUG=353357

Review URL: https://codereview.chromium.org/226373002

git-svn-id: svn://svn.chromium.org/blink/trunk@171378 bbb929c8-8fbe-4397-9dbb-9b2b20218538