Reapply change to update dart2js operator equals semantics to follow

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
diff --git a/lib/compiler/implementation/ssa/builder.dart b/lib/compiler/implementation/ssa/builder.dart
index 6feb3d81e799b1e0508dac5eb6c75cc7aec23a81..4041d33c8e79866db86cb2f6cb5e629ffde6f46a 100644
--- a/lib/compiler/implementation/ssa/builder.dart
+++ b/lib/compiler/implementation/ssa/builder.dart
@@ -97,10 +97,6 @@ class Interceptors {
     return compiler.findHelper(const SourceString('indexSet'));
   }
 
-  Element getEqualsNullInterceptor() {
-    return compiler.findHelper(const SourceString('eqNull'));
-  }
-
   Element getExceptionUnwrapper() {
     return compiler.findHelper(const SourceString('unwrapException'));
   }