DevTools: Replace binarySearch with lowerBound and upperBound functions

This allows to avoid index-mapping-to-negative-axis-trick in
binarySearch and its usages.
It also makes insertionIndexForObjectInListSortedByFunction to work in
O(log(n)) time instead of O(n).

R=caseq@chromium.org

Review URL: https://codereview.chromium.org/18828002

git-svn-id: svn://svn.chromium.org/blink/trunk@153679 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove Image::filenameExtension and related methods; there are no remaining uses of this.

This is used in ClipboardWin.cpp in WebKit (hence the ASSERT), but it is
no longer used anywhere else in Blink.

BUG=257367

Review URL: https://chromiumcodereview.appspot.com/18332018

git-svn-id: svn://svn.chromium.org/blink/trunk@153680 bbb929c8-8fbe-4397-9dbb-9b2b20218538