Remove signature classes from the VM.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1823 matching lines @@
   // R13: instance type arguments or null, used only if n > 1.
   __ movq(RDX, Address(RSP, kCacheOffsetInBytes));
   // RDX: SubtypeTestCache.
   __ movq(RDX, FieldAddress(RDX, SubtypeTestCache::cache_offset()));
   __ addq(RDX, Immediate(Array::data_offset() - kHeapObjectTag));
   // RDX: Entry start.
   // R10: instance class id.
   // R13: instance type arguments.
   Label loop, found, not_found, next_iteration;
   __ SmiTag(R10);
+  __ cmpq(R10, Immediate(Smi::RawValue(kClosureCid)));
+  __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
+  __ movq(R10, FieldAddress(RAX, Closure::function_offset()));
+  // R10: instance class id as Smi or function.
   __ Bind(&loop);
-  __ movq(RDI, Address(RDX, kWordSize * SubtypeTestCache::kInstanceClassId));
+  __ movq(RDI,
+          Address(RDX,
+                  kWordSize * SubtypeTestCache::kInstanceClassIdOrFunction));
   __ cmpq(RDI, R9);
   __ j(EQUAL, &not_found, Assembler::kNearJump);
   __ cmpq(RDI, R10);
   if (n == 1) {
     __ j(EQUAL, &found, Assembler::kNearJump);
   } else {
     __ j(NOT_EQUAL, &next_iteration, Assembler::kNearJump);
     __ movq(RDI,
         Address(RDX, kWordSize * SubtypeTestCache::kInstanceTypeArguments));
     __ cmpq(RDI, R13);
@@ skipping 324 matching lines @@
   __ Bind(&miss);
   __ LoadIsolate(RAX);
   __ movq(CODE_REG, Address(RAX, Isolate::ic_miss_code_offset()));
   __ movq(RCX, FieldAddress(CODE_REG, Code::entry_point_offset()));
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64