Move geometry interface files to geometry directory.

The geometry interfaces such as DOMMatrix, DOMRect and so on can be shared
in a lot of modules such as dom, css and so on. Also, it is not very relevant to
 the DOM, so it is proper to create a new geometry directory and then move the
 related files to the directory.

[1/2] This Patch (Move DOMMatrix related files to geometry folder)
[2/2] https://codereview.chromium.org/2709763004/ (Make WebKitCSSMatrix an
 alias of DOMMatrix.)

BUG=581955

Review-Url: https://codereview.chromium.org/2741723005
Cr-Commit-Position: refs/heads/master@{#459398}
40 files changed