Check for import from previous script.

Source/bindings/dart/DartApplicationLoader.cpp

Index: Source/bindings/dart/DartApplicationLoader.cpp
diff --git a/Source/bindings/dart/DartApplicationLoader.cpp b/Source/bindings/dart/DartApplicationLoader.cpp
index 7f8ef4ccba352ad945b132cc9479bb035eb2cc31..14e34df87ae6fa29a56e588f05b1ce927630f36d 100644
--- a/Source/bindings/dart/DartApplicationLoader.cpp
+++ b/Source/bindings/dart/DartApplicationLoader.cpp
@@ -180,10 +180,15 @@ void DartApplicationLoader::loadMainScript(const String& url, const String& sour
         }
         ASSERT(!Dart_IsNull(script));
 
-        // FIXME(dartbug.com/13460): We need to record the lineOffset and columnOffset.
-        Dart_Handle library = Dart_LoadLibrary(DartUtilities::stringToDartString(url), dartSource);
-        if (Dart_IsError(library))
-            DartUtilities::reportProblem(m_originDocument, library, m_libraryUrl);
+        Dart_Handle libraryUrlHandle = DartUtilities::stringToDartString(url);
+        // Test if a previous script already loaded this library.
+        Dart_Handle library = Dart_LookupLibrary(libraryUrlHandle);
+        if (Dart_IsError(library)) {
+            // FIXME(dartbug.com/13460): We need to record the lineOffset and columnOffset.
+            library = Dart_LoadLibrary(libraryUrlHandle, dartSource);
+            if (Dart_IsError(library))
+                DartUtilities::reportProblem(m_originDocument, library, m_libraryUrl);
+        }
 
         Dart_Handle result = Dart_LibraryImportLibrary(script, library, Dart_Null());
         if (Dart_IsError(result))