Revert r15265 due to checked mode failures.

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

Index: sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/js_backend/backend.dart	(revision 15268)
+++ sdk/lib/_internal/compiler/implementation/js_backend/backend.dart	(working copy)
@@ -658,14 +658,6 @@
   Element jsArrayLength;
   Element jsStringLength;
   Element getInterceptorMethod;
-  Element arrayInterceptor;
-  Element boolInterceptor;
-  Element doubleInterceptor;
-  Element functionInterceptor;
-  Element intInterceptor;
-  Element nullInterceptor;
-  Element numberInterceptor;
-  Element stringInterceptor;
   bool _interceptorsAreInitialized = false;
 
   final Namer namer;
@@ -796,23 +788,6 @@
     jsStringClass.ensureResolved(compiler);
     jsStringLength =
         jsStringClass.lookupLocalMember(const SourceString('length'));
-
-    arrayInterceptor =
-        compiler.findInterceptor(const SourceString('arrayInterceptor'));
-    boolInterceptor =
-        compiler.findInterceptor(const SourceString('boolInterceptor'));
-    doubleInterceptor =
-        compiler.findInterceptor(const SourceString('doubleInterceptor'));
-    functionInterceptor =
-        compiler.findInterceptor(const SourceString('functionInterceptor'));
-    intInterceptor =
-        compiler.findInterceptor(const SourceString('intInterceptor'));
-    nullInterceptor =
-        compiler.findInterceptor(const SourceString('nullInterceptor'));
-    stringInterceptor =
-        compiler.findInterceptor(const SourceString('stringInterceptor'));
-    numberInterceptor =
-        compiler.findInterceptor(const SourceString('numberInterceptor'));
   }
 
   void addInterceptors(ClassElement cls) {