Improved the expression parser's detection of the

current context.  Previously, if there was a variable
called "self" available, the expression parser
assumed it was inside a method.  But class methods
in Objective-C also take a "self" parameter, of DWARF
type "id".  We now detect this properly, and only
assume we're in an instance method if "self" is a
pointer to an Objective-C object.

llvm-svn: 136784