When URL mapping was specified, library loads where not being called for the URLs that were mapped.

bin/process_script.cc

 // Copyright (c) 2011, 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.
 
 // Handle dart scripts.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
@@ skipping 31 matching lines @@
   free(path);
   char* canonical_filename = File::GetCanonicalPath(absolute_filename);
   if (canonical_filename == NULL) {
     return absolute_filename;
   }
   free(absolute_filename);
   return canonical_filename;
 }
 
 
-static const char* CanonicalizeUrl(const char* reference_dir,
-                                   const char* filename) {
-  static const char* kDartScheme = "dart:";
-  static const intptr_t kDartSchemeLen = strlen(kDartScheme);
-  // If the URL starts with "dart:" then it is not modified as it will be
-  // handled by the VM internally.
-  if (strncmp(filename, kDartScheme, kDartSchemeLen) == 0) {
-    return strdup(filename);
-  }
-  return GetCanonicalPath(reference_dir, filename);
-}
-
-
 static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
                                      Dart_Handle library,
                                      Dart_Handle url) {
   if (!Dart_IsLibrary(library)) {
     return Dart_Error("not a library");
   }
   if (!Dart_IsString8(url)) {
     return Dart_Error("url is not a string");
   }
   const char* url_chars = NULL;
   Dart_Handle result = Dart_StringToCString(url, &url_chars);
   if (Dart_IsError(result)) {
     return Dart_Error("accessing url characters failed");
   }
 
+  static const char* kDartScheme = "dart:";
+  static const intptr_t kDartSchemeLen = strlen(kDartScheme);
+  // If the URL starts with "dart:" then it is not modified as it will be
+  // handled by the VM internally.
+  if (strncmp(url_chars, kDartScheme, kDartSchemeLen) == 0) {
+    if (tag == kCanonicalizeUrl) {
+      return url;
+    }
+    return Dart_Error("Do not know how to load '%s'", url_chars);
+  }
   if (tag == kCanonicalizeUrl) {
-    // Create the full path based on the including library and the current url.
+    // Create a canonical path based on the including library and current url.
 
-    // Get the url of the calling library.
+    // Get the url of the including library.
     Dart_Handle library_url = Dart_LibraryUrl(library);
     if (Dart_IsError(library_url)) {
       return Dart_Error("accessing library url failed");
     }
     if (!Dart_IsString8(library_url)) {
       return Dart_Error("library url is not a string");
     }
     const char* library_url_chars = NULL;
     result = Dart_StringToCString(library_url, &library_url_chars);
     if (Dart_IsError(result)) {
       return Dart_Error("accessing library url characters failed");
     }
 
-    // Calculate the path.
-    const char* canon_url_chars = CanonicalizeUrl(library_url_chars, url_chars);
+    // Calculate the canonical path.
+    const char* canon_url_chars = GetCanonicalPath(library_url_chars,
+                                                   url_chars);
     Dart_Handle canon_url = Dart_NewString(canon_url_chars);
     free(const_cast<char*>(canon_url_chars));
 
     return canon_url;
   }
 
   // The tag is either an import or a source tag. Read the file based on the
   // url chars.
   Dart_Handle source = ReadStringFromFile(url_chars);
   if (Dart_IsError(source)) {
@@ skipping 43 matching lines @@
 
 Dart_Handle LoadScript(const char* script_name) {
   Dart_Handle source = ReadStringFromFile(script_name);
   if (Dart_IsError(source)) {
     return source;
   }
   Dart_Handle url = Dart_NewString(script_name);
 
   return Dart_LoadScript(url, source, LibraryTagHandler);
 }