dart2js: Inline across deferred output units if that leads to reduced size.

pkg/compiler/lib/src/deferred_load.dart

 // Copyright (c) 2014, 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.
 
 library deferred_load;
 
 import 'constants/expressions.dart';
 import 'constants/values.dart' show
     ConstantValue,
     ConstructedConstantValue,
@@ skipping 183 matching lines @@
   /// Returns the [OutputUnit] where [constant] belongs.
   OutputUnit outputUnitForConstant(ConstantValue constant) {
     if (!isProgramSplit) return mainOutputUnit;
     return _constantToOutputUnit[constant];
   }
 
   bool isDeferred(Element element) {
     return outputUnitForElement(element) != mainOutputUnit;
   }
 
-  /// Returns true if e1 and e2 are in the same output unit.
-  bool inSameOutputUnit(Element e1, Element e2) {
-    return outputUnitForElement(e1) == outputUnitForElement(e2);
+  /// Returns `true` if element [to] is reachable from element [from] without
+  /// crossing a deferred import.
+  ///
+  /// For example, if we have two deferred libraries `A` and `B` that both
+  /// import a library `C`, then even though elements from `A` and `C` end up in
+  /// different output units, there is a non-deferred path between `A` and `C`.
+  bool hasOnlyNonDeferredImportPaths(Element from, Element to) {
+    OutputUnit outputUnitFrom = outputUnitForElement(from);
+    OutputUnit outputUnitTo = outputUnitForElement(to);
+    return outputUnitTo.imports.containsAll(outputUnitFrom.imports);
+  }
+
+  bool isFromMainOutputUnit(Element element) {
+    return outputUnitForElement(element) == mainOutputUnit;
   }
 
   void registerConstantDeferredUse(DeferredConstantValue constant,
                                    PrefixElement prefix) {
     OutputUnit outputUnit = new OutputUnit();
     outputUnit.imports.add(prefix.deferredImport);
     _constantToOutputUnit[constant] = outputUnit;
   }
 
   /// Answers whether [element] is explicitly deferred when referred to from
@@ skipping 665 matching lines @@
         _importingLibrary = importingLibrary;
 
   String get importingLibraryName {
     String libraryName = _importingLibrary.getLibraryName();
     return libraryName == ""
       ? "<unnamed>"
       : libraryName;
   }
 
 }