Improve WebSQL's 'openDatabase' exception messages.

This patch flips WebDatabase over to 'es.throwSecurityError()' for those
SecurityError exceptions that appear, and pipes through any error
message that the backend has thrown.

It also drops a few unused (?) error types that mapped to SecurityError.

BUG=152212

Review URL: https://chromiumcodereview.appspot.com/23064015

git-svn-id: svn://svn.chromium.org/blink/trunk@158370 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Improve exception error messages in DOMTokenList.

BUG=270033

Review URL: https://chromiumcodereview.appspot.com/23609063

git-svn-id: svn://svn.chromium.org/blink/trunk@158371 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Cleanup: Move form-related localized string functions from LocalizedStrings to Locale.

I found fileButtonNoFilesSelectedLabel() and fileButtonNoFileSelectedLabel()
requested an identical string. This patch removes some condition checks for
HTMLInputElement::multiple().

BUG=298020
TEST=none; no behavior changes.

Review URL: https://chromiumcodereview.appspot.com/24723002

git-svn-id: svn://svn.chromium.org/blink/trunk@158372 bbb929c8-8fbe-4397-9dbb-9b2b20218538