fix a crash on:

let Constraints = "$val = $dst", Defs = [EFLAGS] in, isCodeGenOnly = 1 {

we now get:

X86InstrCompiler.td:653:52: error: Expected class, def, defm, multiclass or let definition
let Constraints = "$val = $dst", Defs = [EFLAGS] in, isCodeGenOnly = 1 {
                                                   ^

llvm-svn: 117863
diff --git a/llvm/utils/TableGen/TGParser.cpp b/llvm/utils/TableGen/TGParser.cpp
index 7bd2fbc..22afca1 100644
--- a/llvm/utils/TableGen/TGParser.cpp
+++ b/llvm/utils/TableGen/TGParser.cpp
@@ -2087,7 +2087,8 @@
 ///   Object ::= LETCommand Object
 bool TGParser::ParseObject(MultiClass *MC) {
   switch (Lex.getCode()) {
-  default: assert(0 && "This is not an object");
+  default:
+    return TokError("Expected class, def, defm, multiclass or let definition");
   case tgtok::Let:   return ParseTopLevelLet(MC);
   case tgtok::Def:   return ParseDef(MC);
   case tgtok::Defm:  return ParseDefm(MC);