<rdar://problem/16006373>

Revert the spirit of r199857 - a convincing case can be made that overriding a summary's format markers behind its back is not the right thing to do
This commit reverts the behavior of the code to the previous model, and changes the test case to validate the opposite of what it was validating before



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@201455 91177308-0d34-0410-b5e6-96231b3b80d8