This is an overhaul of the expression parser code

that detects what context the current expression is
meant to execute in.  LLDB now properly consults
the method declaration in the debug information
rather than trying to hunt down the "this" or "self"
pointer by name, which can be misleading.

Other fixes include:

- LLDB now properly detects that it is inside
  an inlined C++ member function.

- LLDB now allows access to non-const members when
  in const code.

- The functions in SymbolFile that locate the
  DeclContext containing a DIE have been renamed
  to reflect what they actually do.  I have added
  new functions that find the DeclContext for the
  DIE itself.

I have also introduced testcases for C++ and 
Objective-C.

llvm-svn: 136999