[pkg:js] Disable JS/Native class conflict check

Bug: https://github.com/dart-lang/sdk/issues/44778

The Native/JS class conflict check breaks user behavior. It should
instead be added under a language version to avoid a breakage on
SDK update. This CL simply disables the check always so that it can
be a simpler cherry-pick for 2.12.

Change-Id: I40b0a3a4c46b1442257028c99360ef0ed0b4154c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/181440
Reviewed-by: Riley Porter <rileyporter@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
diff --git a/pkg/_js_interop_checks/lib/js_interop_checks.dart b/pkg/_js_interop_checks/lib/js_interop_checks.dart
index e3f0978..b936c44 100644
--- a/pkg/_js_interop_checks/lib/js_interop_checks.dart
+++ b/pkg/_js_interop_checks/lib/js_interop_checks.dart
@@ -30,6 +30,9 @@
   bool _classHasAnonymousAnnotation = false;
   bool _libraryHasJSAnnotation = false;
   bool _libraryIsGlobalNamespace = false;
+  // TODO(srujzs): This currently disables this check always. This check should
+  // instead only be disabled up until a given language version.
+  bool _disableJSNativeClassConflict = true;
 
   JsInteropChecks(
       this._coreTypes, this._diagnosticsReporter, this._nativeClasses);
@@ -83,7 +86,8 @@
             cls.location.file);
       }
     }
-    if (_classHasJSAnnotation &&
+    if (!_disableJSNativeClassConflict &&
+        _classHasJSAnnotation &&
         !_classHasAnonymousAnnotation &&
         _libraryIsGlobalNamespace) {
       var jsClass = getJSName(cls);