This patch fixes our lldb pretty printer for WTF::Vector. In
https://codereview.chromium.org/13900002 cevans changed Vector but our lldb
script hasn't been updated.

Before:
(WebCore::NodeVector) $8 = {
  m_size = 1
  m_buffer = 0xbffdc2ac
}

After:
(WebCore::NodeVector) $11 = {
  [0] = {
    m_ptr = 0x4ff060b8
  }
  m_size = 1
  m_capacity = 11
  m_buffer = 0xbffdc2ac
}

This is primarily a merge of wkrev.com/150455 by jer.noble@apple.com.

Review URL: https://codereview.chromium.org/191893002

git-svn-id: svn://svn.chromium.org/blink/trunk@169097 bbb929c8-8fbe-4397-9dbb-9b2b20218538