spawnUri. Take two. This time I'll wait for Anton before committing :-).

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
===================================================================
--- runtime/include/dart_api.h	(revision 7916)
+++ runtime/include/dart_api.h	(working copy)
@@ -389,22 +389,41 @@
 /**
  * An isolate creation and initialization callback function.
  *
- * This callback, provided by the embedder, is called when an isolate needs
- * to be created. The callback should create an isolate and load the
- * required scripts for execution.
+ * This callback, provided by the embedder, is called when the vm
+ * needs to create an isolate. The callback should create an isolate
+ * by calling Dart_CreateIsolate and load any scripts required for
+ * execution.
  *
+ * When the function returns false, it is the responsibility of this
+ * function to ensure that Dart_ShutdownIsolate has been called if
+ * required (for example, if the isolate was created successfully by
+ * Dart_CreateIsolate() but the root library fails to load
+ * successfully, then the function should call Dart_ShutdownIsolate
+ * before returning).
+ *
+ * When the function returns false, the function should set *error to
+ * a malloc-allocated buffer containing a useful error message.  The
+ * caller of this function (the vm) will make sure that the buffer is
+ * freed.
+ *
+ * \param script_uri The uri of the script to load.  This uri has been
+ *   canonicalized by the library tag handler from the parent isolate.
+ *   The callback is responsible for loading this script by a call to
+ *   Dart_LoadScript or Dart_LoadScriptFromSnapshot.
+ * \param main The name of the main entry point this isolate will
+ *   eventually run.  This is provided for advisory purposes only to
+ *   improve debugging messages.  The main function is not invoked by
+ *   this function.
+ * \param callback_data The callback data which was passed to the
+ *   parent isolate when it was created by calling Dart_CreateIsolate().
  * \param error A structure into which the embedder can place a
  *   C string containing an error message in the case of failures.
  *
- * \return The embedder returns false if the creation and initialization was not
- *   successful and true if successful. The embedder is responsible for
- *   maintaining consistency in the case of errors (e.g: isolate is created,
- *   but loading of scripts fails then the embedder should ensure that
- *   Dart_ShutdownIsolate is called on the isolate).
- *   In the case of errors the caller is responsible for freeing the buffer
- *   returned in error containing an error string.
+ * \return The embedder returns false if the creation and
+ *   initialization was not successful and true if successful.
  */
-typedef bool (*Dart_IsolateCreateCallback)(const char* name_prefix,
+typedef bool (*Dart_IsolateCreateCallback)(const char* script_uri,
+                                           const char* main,
                                            void* callback_data,
                                            char** error);
 
@@ -478,13 +497,22 @@
  *
  * Requires there to be no current isolate.
  *
+ * \param script_uri The name of the script this isolate will load.
+ *   Provided only for advisory purposes to improve debugging messages.
+ * \param main The name of the main entry point this isolate will run.
+ *   Provided only for advisory purposes to improve debugging messages.
  * \param snapshot A buffer containing a VM snapshot or NULL if no
  *   snapshot is provided.
+ * \param callback_data Embedder data.  This data will be passed to
+ *   the Dart_IsolateCreateCallback when new isolates are spawned from
+ *   this parent isolate.
+ * \param error DOCUMENT
  *
  * \return The new isolate is returned. May be NULL if an error
  *   occurs duing isolate initialization.
  */
-DART_EXPORT Dart_Isolate Dart_CreateIsolate(const char* name_prefix,
+DART_EXPORT Dart_Isolate Dart_CreateIsolate(const char* script_uri,
+                                            const char* main,
                                             const uint8_t* snapshot,
                                             void* callback_data,
                                             char** error);
@@ -1923,13 +1951,12 @@
 // TODO(turnidge): Document.
 typedef Dart_Handle (*Dart_LibraryTagHandler)(Dart_LibraryTag tag,
                                               Dart_Handle library,
-                                              Dart_Handle url,
-                                              Dart_Handle import_map);
+                                              Dart_Handle url);
 
 /**
- * Set library tag handler for the current isolate. This handler is used to
- * handle the various tags encountered while loading libraries or scripts in
- * the isolate.
+ * Sets library tag handler for the current isolate. This handler is
+ * used to handle the various tags encountered while loading libraries
+ * or scripts in the isolate.
  *
  * \param handler Handler code to be used for handling the various tags
  *   encountered while loading libraries or scripts in the isolate.
@@ -1943,13 +1970,38 @@
     Dart_LibraryTagHandler handler);
 
 /**
+ * Sets the import map for the current isolate.
+ *
+ * The import map is a List of Strings, representing a set of (name,
+ * value) pairs. The import map is used during the resolution of #
+ * directives in source files to implement string interpolation.
+ *
+ * For example, if a source file imports:
+ *
+ *   #import('${foo}/dart.html');
+ *
+ * And the import map is:
+ *
+ *   [ "foo", "/home/user" ]
+ *
+ * Then the import would resolve to:
+ *
+ *   #import('/home/user/dart.html');
+ *
+ * \param import_map A List of Strings interpreted as a String to
+ *   String mapping.
+ * \return If no error occurs, the import map is set for the isolate.
+ *   Otherwise an error handle is returned.
+ */
+DART_EXPORT Dart_Handle Dart_SetImportMap(Dart_Handle import_map);
+
+/**
  * Loads the root script for the current isolate.
  *
  * TODO(turnidge): Document.
  */
 DART_EXPORT Dart_Handle Dart_LoadScript(Dart_Handle url,
-                                        Dart_Handle source,
-                                        Dart_Handle import_map);
+                                        Dart_Handle source);
 
 /**
  * Loads the root script for current isolate from a snapshot.
@@ -1958,10 +2010,19 @@
  *
  * \return If no error occurs, the Library object corresponding to the root
  *   script is returned. Otherwise an error handle is returned.
- **/
+ */
 DART_EXPORT Dart_Handle Dart_LoadScriptFromSnapshot(const uint8_t* buffer);
 
 /**
+ * Gets the library for the root script for the current isolate.
+ *
+ * \return Returns the Library object corresponding to the root script
+ *   if it has been set by a successful call to Dart_LoadScript or
+ *   Dart_LoadScriptFromSnapshot.  Otherwise returns Dart_Null().
+ */
+DART_EXPORT Dart_Handle Dart_RootLibrary();
+
+/**
  * Forces all loaded classes and functions to be compiled eagerly in
  * the current isolate..
  *
@@ -1991,8 +2052,7 @@
 // not found to distinguish that from a true error case.
 
 DART_EXPORT Dart_Handle Dart_LoadLibrary(Dart_Handle url,
-                                         Dart_Handle source,
-                                         Dart_Handle import_map);
+                                         Dart_Handle source);
 
 
 DART_EXPORT Dart_Handle Dart_LibraryImportLibrary(Dart_Handle library,