Use index in J/KTypeVariable and fix remaining inequivalence

pkg/compiler/lib/src/js_backend/backend.dart

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index bdffc10ac89d597061aee850fe20311f7429ae4b..aa761c550cb717dcdfad4d91a41bbe27ae6728cf 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -686,10 +686,6 @@ class JavaScriptBackend {
         !mirrorsData.invokedReflectively(method);
   }
 
-  bool operatorEqHandlesNullArgument(FunctionEntity operatorEqfunction) {
-    return specialOperatorEqClasses.contains(operatorEqfunction.enclosingClass);
-  }
-
   void validateInterceptorImplementsAllObjectMethods(
       ClassEntity interceptorClass) {
     if (interceptorClass == null) return;
@@ -1055,11 +1051,6 @@ class JavaScriptBackend {
       // These methods are overwritten with generated versions.
       inlineCache.markAsNonInlinable(commonElements.getInterceptorMethod,
           insideLoop: true);
-
-      specialOperatorEqClasses
-        ..add(commonElements.objectClass)
-        ..add(commonElements.jsInterceptorClass)
-        ..add(commonElements.jsNullClass);
     }
   }