Support multiple resolution inputs from command line.

pkg/compiler/lib/src/serialization/modelz.dart

Index: pkg/compiler/lib/src/serialization/modelz.dart
diff --git a/pkg/compiler/lib/src/serialization/modelz.dart b/pkg/compiler/lib/src/serialization/modelz.dart
index 75bdbf357ac7c51f4b718f5c8aa02c89706cb7f3..0c06ea4b821a422970523ebf53370456b90fc40a 100644
--- a/pkg/compiler/lib/src/serialization/modelz.dart
+++ b/pkg/compiler/lib/src/serialization/modelz.dart
@@ -371,6 +371,9 @@ class LibraryElementZ extends DeserializedElementZ
   String get name => entryCompilationUnit.name;
 
   @override
+  SourceSpan get sourcePosition => entryCompilationUnit.sourcePosition;
+
+  @override
   accept(ElementVisitor visitor, arg) {
     return visitor.visitLibraryElement(this, arg);
   }
@@ -557,6 +560,9 @@ class CompilationUnitElementZ extends DeserializedElementZ
   Element get enclosingElement => library;
 
   @override
+  SourceSpan get sourcePosition => new SourceSpan(script.resourceUri, 0, 0);
+
+  @override
   accept(ElementVisitor visitor, arg) {
     return visitor.visitCompilationUnitElement(this, arg);
   }