Add StaticUse for more precise registration of statically known element use.

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

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 /**
  * Support for Custom Elements.
  *
  * The support for custom elements the compiler builds a table that maps the
@@ skipping 138 matching lines @@
     for (ClassElement classElement in instantiatedClasses) {
       bool isNative = backend.isNative(classElement);
       bool isExtension =
           !isNative && backend.isNativeOrExtendsNative(classElement);
       // Generate table entries for native classes that are explicitly named and
       // extensions that fix our criteria.
       if ((isNative && selectedClasses.contains(classElement)) ||
           (isExtension &&
               (allClassesSelected || selectedClasses.contains(classElement)))) {
         newActiveClasses.add(classElement);
-        Iterable<Element> escapingConstructors =
+        Iterable<ConstructorElement> escapingConstructors =
             computeEscapingConstructors(classElement);
-        escapingConstructors.forEach(enqueuer.registerStaticUse);
+        for (ConstructorElement constructor in escapingConstructors) {
+          enqueuer.registerStaticUse(new StaticUse.foreignUse(constructor));
+        }
         escapingConstructors
             .forEach(compiler.globalDependencies.registerDependency);
         // Force the generaton of the type constant that is the key to an entry
         // in the generated table.
         ConstantValue constant = makeTypeConstant(classElement);
         backend.registerCompileTimeConstant(
             constant, compiler.globalDependencies);
         backend.addCompileTimeConstantForEmission(constant);
       }
     }
     activeClasses.addAll(newActiveClasses);
     instantiatedClasses.removeAll(newActiveClasses);
   }
 
   TypeConstantValue makeTypeConstant(ClassElement element) {
     DartType elementType = element.rawType;
     return backend.constantSystem.createType(compiler, elementType);
   }
 
-  List<Element> computeEscapingConstructors(ClassElement classElement) {
-    List<Element> result = <Element>[];
+  List<ConstructorElement> computeEscapingConstructors(
+      ClassElement classElement) {
+    List<ConstructorElement> result = <ConstructorElement>[];
     // Only classes that extend native classes have constructors in the table.
     // We could refine this to classes that extend Element, but that would break
     // the tests and there is no sane reason to subclass other native classes.
     if (backend.isNative(classElement)) return result;
 
-    selectGenerativeConstructors(ClassElement enclosing, Element member) {
+    void selectGenerativeConstructors(ClassElement enclosing, Element member) {
       if (member.isGenerativeConstructor) {
         // Ignore constructors that cannot be called with zero arguments.
-        FunctionElement constructor = member;
+        ConstructorElement constructor = member;
         constructor.computeType(compiler.resolution);
         FunctionSignature parameters = constructor.functionSignature;
         if (parameters.requiredParameterCount == 0) {
           result.add(member);
         }
       }
     }
     classElement.forEachMember(selectGenerativeConstructors,
         includeBackendMembers: false,
         includeSuperAndInjectedMembers: false);
     return result;
   }
 }