Remove holders for runtime type information.

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

 // Copyright (c) 2011, 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.
 
 part of js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 618 matching lines @@
         name = '$unminifiedName$level';
       }
       name = getMappedInstanceName(name);
     }
     bailoutNames[element] = name;
     return name;
   }
 
   /// Returns the runtime name for [element].  The result is not safe as an id.
   String getRuntimeTypeName(Element element) {
-    if (element == compiler.intClass) {
+    JavaScriptBackend backend = compiler.backend;
+    element = backend.getImplementationClass(element);
+    String name = getPrimitiveInterceptorRuntimeName(element);
+    return name != null ? name : getName(element);
+  }
+
+  /**
+   * Return a string to be used as the runtime name of this class (instead of
+   * the class name) or [null] if the class name should be used.
+   */
+  String getPrimitiveInterceptorRuntimeName(Element cls) {
+    JavaScriptBackend backend = compiler.backend;
+    if (cls == backend.jsIntClass) {
       return 'int';
-    } else if (element == compiler.doubleClass) {
+    } else if (cls == backend.jsNumberClass) {
+      return 'num';
+    } else if (cls == backend.jsBoolClass) {
+      return 'bool';
+    } else if (cls == backend.jsDoubleClass) {
       return 'double';
+    } else if (cls == backend.jsStringClass) {
+      return 'String';
+    } else if (cls == backend.jsArrayClass) {
+      return 'List';
     } else {
-      return getName(element);
+      return null;
     }
   }
 
   /**
    * Returns a preferred JS-id for the given element. The returned id is
    * guaranteed to be a valid JS-id. Globals and static fields are furthermore
    * guaranteed to be unique.
    *
    * For accessing statics consider calling
    * [isolateAccess]/[isolateBailoutAccess] or [isolatePropertyAccess] instead.
@@ skipping 469 matching lines @@
     hash = hash ^ (hash >> 6);
     return hash;
   }
 
   static int _finish(int hash) {
     hash = _MASK & (hash + (((_MASK >> 3) & hash) <<  3));
     hash = hash & (hash >> 11);
     return _MASK & (hash + (((_MASK >> 15) & hash) << 15));
   }
 }