Jen Zajac authored Sep 14, 2015 and Robert Lyon committed Sep 14, 2015

  The dock's close button doesn't have the id in it
  needed to remove new (unsaved) blocks.

  This fix passes the block id in, so the new block
  can be cleaned up when a user changes their mind
  and removes it before saving.

  To test: add a new text block to a page, click the
  X icon in the top left of the dock, and observe
  that the new text block is removed from the page.

  The delete buttons next to each on page item, and
  the cancel button within the dock, should both
  still function as before.

  behatnotneeded

  Bug 1465107

Change-Id: I81f3b43acce9203b8ada9b3f7ac9b6cacb80768c