- Use a map to lookup libraries by URL.

runtime/vm/bootstrap.cc

Index: runtime/vm/bootstrap.cc
diff --git a/runtime/vm/bootstrap.cc b/runtime/vm/bootstrap.cc
index 9bde826d7d505d05aee7b74c134730cf0c65705a..ed97340f8e254946e1a2e7c78c499f3319702664 100644
--- a/runtime/vm/bootstrap.cc
+++ b/runtime/vm/bootstrap.cc
@@ -301,11 +301,11 @@ RawError* Bootstrap::LoadandCompileScripts() {
     }
 #endif  // !PRODUCT
     uri = Symbols::New(thread, bootstrap_libraries[i].uri_);
-    lib = Library::LookupLibrary(uri);
+    lib = Library::LookupLibrary(thread, uri);
     if (lib.IsNull()) {
       lib = Library::NewLibraryHelper(uri, false);
       lib.SetLoadRequested();
-      lib.Register();
+      lib.Register(thread);
     }
     isolate->object_store()->set_bootstrap_library(
         bootstrap_libraries[i].index_, lib);
@@ -321,7 +321,7 @@ RawError* Bootstrap::LoadandCompileScripts() {
     }
 #endif  // PRODUCT
     uri = Symbols::New(thread, bootstrap_libraries[i].uri_);
-    lib = Library::LookupLibrary(uri);
+    lib = Library::LookupLibrary(thread, uri);
     ASSERT(!lib.IsNull());
     source = GetLibrarySource(lib, uri, false);
     if (source.IsNull()) {