Revert r42145 to fix co19 tests

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 42146)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -23,8 +23,6 @@
 namespace dart {
 
 DECLARE_FLAG(bool, emit_edge_counters);
-DECLARE_FLAG(bool, enable_asserts);
-DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(int, optimization_counter_threshold);
 DECLARE_FLAG(bool, propagate_ic_data);
 DECLARE_FLAG(bool, throw_on_javascript_int_overflow);
@@ -331,18 +329,11 @@
   // Call the runtime if the object is not bool::true or bool::false.
   ASSERT(locs->always_calls());
   Label done;
+  __ CompareObject(reg, Bool::True(), PP);
+  __ j(EQUAL, &done, Assembler::kNearJump);
+  __ CompareObject(reg, Bool::False(), PP);
+  __ j(EQUAL, &done, Assembler::kNearJump);
 
-  if (FLAG_enable_type_checks) {
-    __ CompareObject(reg, Bool::True(), PP);
-    __ j(EQUAL, &done, Assembler::kNearJump);
-    __ CompareObject(reg, Bool::False(), PP);
-    __ j(EQUAL, &done, Assembler::kNearJump);
-  } else {
-    ASSERT(FLAG_enable_asserts);
-    __ CompareObject(reg, Object::null_instance(), PP);
-    __ j(NOT_EQUAL, &done, Assembler::kNearJump);
-  }
-
   __ pushq(reg);  // Push the source object.
   compiler->GenerateRuntimeCall(token_pos,
                                 deopt_id,