Support creating elements from IR nodes in JsKernelToElementMap

pkg/compiler/lib/src/common_elements.dart

Index: pkg/compiler/lib/src/common_elements.dart
diff --git a/pkg/compiler/lib/src/common_elements.dart b/pkg/compiler/lib/src/common_elements.dart
index 760f5d16c2dc7a90abdfcf26d468bf97fe1a9512..1afef190d15917ce852c06f2f934b51050542c36 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -942,15 +942,32 @@ class CommonElements {
   FunctionEntity get throwConcurrentModificationError =>
       _findHelperFunction('throwConcurrentModificationError');
 
-  FunctionEntity _checkInt;
-  FunctionEntity get checkInt => _checkInt ??= _findHelperFunction('checkInt');
+  /// Return `true` if [member] is the 'checkInt' function defined in
+  /// dart:_js_helpers.
+  bool isCheckInt(MemberEntity member) {
+    return member.isFunction &&
+        member.isTopLevel &&
+        member.library == jsHelperLibrary &&
+        member.name == 'checkInt';
+  }
 
-  FunctionEntity _checkNum;
-  FunctionEntity get checkNum => _checkNum ??= _findHelperFunction('checkNum');
+  /// Return `true` if [member] is the 'checkNum' function defined in
+  /// dart:_js_helpers.
+  bool isCheckNum(MemberEntity member) {
+    return member.isFunction &&
+        member.isTopLevel &&
+        member.library == jsHelperLibrary &&
+        member.name == 'checkNum';
+  }
 
-  FunctionEntity _checkString;
-  FunctionEntity get checkString =>
-      _checkString ??= _findHelperFunction('checkString');
+  /// Return `true` if [member] is the 'checkString' function defined in
+  /// dart:_js_helpers.
+  bool isCheckString(MemberEntity member) {
+    return member.isFunction &&
+        member.isTopLevel &&
+        member.library == jsHelperLibrary &&
+        member.name == 'checkString';
+  }
 
   FunctionEntity get stringInterpolationHelper => _findHelperFunction('S');