Fix wrong canonicalization of signature class due to name collision (issue 6353).

runtime/vm/raw_object.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/token.h"
@@ skipping 1013 matching lines @@
 
 class RawTypeParameter : public RawAbstractType {
  private:
   RAW_HEAP_OBJECT_IMPLEMENTATION(TypeParameter);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->parameterized_class_);
   }
   RawClass* parameterized_class_;
   RawString* name_;
-  RawAbstractType* bound_;  // DynamicType if no explicit bound specified.
+  RawAbstractType* bound_;  // ObjectType if no explicit bound specified.
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->bound_); }
   intptr_t index_;
   intptr_t token_pos_;
   int8_t type_state_;
 };
 
 
 class RawNumber : public RawInstance {
   RAW_OBJECT_IMPLEMENTATION(Number);
 };
@@ skipping 562 matching lines @@
          kExternalUint64ArrayCid == kByteArrayCid + 18 &&
          kExternalFloat32ArrayCid == kByteArrayCid + 19 &&
          kExternalFloat64ArrayCid == kByteArrayCid + 20 &&
          kStacktraceCid == kByteArrayCid + 21);
   return (index >= kByteArrayCid && index <= kExternalFloat64ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_