Insert checks before deferred calls and accesses.

sdk/lib/_internal/compiler/implementation/compile_time_constants.dart

 // Copyright (c) 2012, 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 dart2js;
 
 /// A [ConstantEnvironment] provides access for constants compiled for variable
 /// initializers.
 abstract class ConstantEnvironment {
   /// Returns the constant for the initializer of [element].
@@ skipping 399 matching lines @@
   Constant makeTypeConstant(TypeDeclarationElement element) {
     DartType elementType = element.rawType;
     DartType constantType =
         compiler.backend.typeImplementation.computeType(compiler);
     return new TypeConstant(elementType, constantType);
   }
 
   /// Returns true if the prefix of the send resolves to a deferred import
   /// prefix.
   bool isDeferredUse(Send send) {
-    // We handle:
-    // 1. Send(Send(Send(null, Prefix), className), staticName)
-    // 2. Send(Send(Prefix, Classname), staticName)
-    // 3. Send(Send(null, Prefix), staticName | className)
-    // 4. Send(Send(Prefix), staticName | className)
-    // Nodes of the forms 2,4 occur in metadata.
     if (send == null) return false;
-    while (send.receiver is Send) {
-      send = send.receiver;
-    }
-    Identifier prefixNode;
-    if (send.receiver is Identifier) {
-      prefixNode = send.receiver;
-    } else if (send.receiver == null &&
-        send.selector is Identifier) {
-      prefixNode = send.selector;
-    }
-    if (prefixNode != null) {
-      Element maybePrefix = elements[prefixNode.asIdentifier()];
-      if (maybePrefix != null && maybePrefix.isPrefix() &&
-          (maybePrefix as PrefixElement).isDeferred) {
-        return true;
-      }
-    }
-    return false;
+    return compiler.deferredLoadTask
+        .deferredPrefixElement(send, elements) != null;
   }
 
   Constant visitIdentifier(Identifier node) {
     Element element = elements[node];
     if (Elements.isClass(element) || Elements.isTypedef(element)) {
       return makeTypeConstant(element);
     }
     return signalNotCompileTimeConstant(node);
   }
 
@@ skipping 534 matching lines @@
           if (fieldValue == null) {
             // Use the default value.
             fieldValue = handler.compileConstant(field);
           }
           jsNewArguments.add(fieldValue);
         },
         includeSuperAndInjectedMembers: true);
     return jsNewArguments;
   }
 }