Bug 1016184 part 3f - Fix test_paste_selection.html

To avoid touch caret interfering with the synthesized mouse event, add
spaces between <input> fields so that touch caret won't cover them.
Bug 1016184 part 3g - Enlarge expiration time in mochitest and reftest
Bug 1016184 part 4 - Enable touch caret by default on b2g