Refactor how the "length" parameter is obtained for HmacKeyParams.

This makes it more clear to the caller that the length parameter is optional and may not be present. Being more defensive is desirable, since I saw a code review which tried to use the value without checking if it was present.

BUG=245025

Review URL: https://chromiumcodereview.appspot.com/23455017

git-svn-id: svn://svn.chromium.org/blink/trunk@156972 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: use screenshot's viewport for coordinate conversion.

R=vsevik@chromium.org

Review URL: https://codereview.chromium.org/23672018

git-svn-id: svn://svn.chromium.org/blink/trunk@156973 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Cleanup: Remove deprecated method.

BUG=245025

Review URL: https://chromiumcodereview.appspot.com/23503013

git-svn-id: svn://svn.chromium.org/blink/trunk@156974 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Refactoring: Rename 'Alias' to 'PastNames'.

'Past names' is a term used in the standard. [1]
This imports a part of WebKit r154586 by rniwa. [2]

[1] http://www.whatwg.org/specs/web-apps/current-work/multipage/forms.html#dom-form-nameditem
[2] http://trac.webkit.org/changeset/154586

BUG=190026
TEST=none; no behavior changes.

Review URL: https://chromiumcodereview.appspot.com/23726008

git-svn-id: svn://svn.chromium.org/blink/trunk@156975 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Cleanup: Make Platform::crypto() required.

The feature can be turned off via a runtime flag, so not much to be gained by allowing NULL when it is on.

BUG=245025

Review URL: https://chromiumcodereview.appspot.com/23798002

git-svn-id: svn://svn.chromium.org/blink/trunk@156976 bbb929c8-8fbe-4397-9dbb-9b2b20218538