[GeometryInterface] Add Constructor() at DOMMatrixReadOnly.

Return the result of invoking create a 2d matrix of type
DOMMatrixReadOnly, with the sequence [1, 0, 0, 1, 0, 0].

spec list:
https://drafts.fxtf.org/geometry/#dom-dommatrixreadonly-dommatrixreadonly

BUG=388780, 665436

Review-Url: https://codereview.chromium.org/2504543003
Cr-Commit-Position: refs/heads/master@{#433099}
5 files changed