Fix crash when a script request a resource missing from an mhtml archive.

This was probably regressed in r151344.

BUG=247091
TEST=mhtml/new-image-not-in-archive.mht
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/17206004

git-svn-id: svn://svn.chromium.org/blink/trunk@153689 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Rename ExceptionCode constants to use the names in the spec

For example:

INDEX_SIZE_ERR -> IndexSizeError

Patch 2 of 3

BUG=None
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/18548003

git-svn-id: svn://svn.chromium.org/blink/trunk@153690 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add unit testing to parseFrameSetListOfDimensions

This is a preparatory step towards introducing HTMLDimension and
implementing the HTML5 algorithm to parse a list of dimensions. The
new test will enable us to track the differences as we make the
switch.

Review URL: https://chromiumcodereview.appspot.com/18084006

git-svn-id: svn://svn.chromium.org/blink/trunk@153691 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move DataStoreFile's db calls to asychronous API.

Refactor DataStoreFile's calls to get(), put(), and delete() to
use their asynchronous versions.

Add unit tests for save_data(), load_data(), and delete_data().

Through the magic of git, I ran the unit tests against the old
code and the new code both.

BUG=252376

Review URL: https://chromiumcodereview.appspot.com/18042004

git-svn-id: svn://svn.chromium.org/blink/trunk@153692 bbb929c8-8fbe-4397-9dbb-9b2b20218538