Removed a bad assertion:

assert(((SymbolFileDWARF*)m_ast.GetSymbolFile())->UserIDMatches(die.GetDIERef().GetUID()) &&
       "Adding incorrect type to forward declaration map");

The problem is that "m_ast.GetSymbolFile()" can return a SymbolFileDWARFDebugMap. The code is doing the right thing if the assertion is ignored.

<rdar://problem/24437972>

llvm-svn: 260618