DevTools: Make WebInspector.RegExpSetting store array of regexp internally.

We use this setting for framework blackboxing and workspace folder exclude pattern,
and both settings actually operate over array of regexps.

This will be needed when we implement regexp UI dialog.

R=vsevik

Review URL: https://codereview.chromium.org/365073002

git-svn-id: svn://svn.chromium.org/blink/trunk@177518 bbb929c8-8fbe-4397-9dbb-9b2b20218538
gardening: mark loader/data-uri-images-load-when-loading-images-automatically-disabled.html as slow

BUG=391388
TBR=mnaganov@chromium.org

Review URL: https://codereview.chromium.org/371523005

git-svn-id: svn://svn.chromium.org/blink/trunk@177519 bbb929c8-8fbe-4397-9dbb-9b2b20218538