Formatter: Initial support for formatting Objective-C method expressions.        
                                                                                 
This follows the approach suggested by djasper in PR14911: When a '[' is         
seen that's at the start of a line, follows a binary operator, or follows one    
of : [ ( return throw, that '[' and its closing ']' are marked as
TT_ObjCMethodExpr and every ':' in that range that isn't part of a ternary
?: is marked as TT_ObjCMethodExpr as well.

Update the layout routines to not output spaces around ':' tokens that are
marked TT_ObjCMethodExpr, and only allow breaking after such tokens, not
before.

Before:
    [self adjustButton : closeButton_ ofKind : NSWindowCloseButton];

Now:
    [self adjustButton:closeButton_ ofKind:NSWindowCloseButton];



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172304 91177308-0d34-0410-b5e6-96231b3b80d8