Represent tokens as a compressed stream instead of an array.

vm/snapshot.cc

Index: vm/snapshot.cc
===================================================================
--- vm/snapshot.cc	(revision 9303)
+++ vm/snapshot.cc	(working copy)
@@ -82,6 +82,7 @@
       library_(Library::Handle()),
       type_(AbstractType::Handle()),
       type_arguments_(AbstractTypeArguments::Handle()),
+      tokens_(Array::Handle()),
       backward_references_((snapshot->kind() == Snapshot::kFull) ?
                            kNumInitialReferencesInFullSnapshot :
                            kNumInitialReferences) {
@@ -329,9 +330,13 @@
 
 
 RawTokenStream* SnapshotReader::NewTokenStream(intptr_t len) {
-  ALLOC_NEW_OBJECT_WITH_LEN(TokenStream,
-                            Object::token_stream_class(),
-                            len);
+  ASSERT(kind_ == Snapshot::kFull);
+  ASSERT(isolate()->no_gc_scope_depth() != 0);
+  cls_ = Object::token_stream_class();
+  RawTokenStream* obj = reinterpret_cast<RawTokenStream*>(
+      AllocateUninitialized(cls_, TokenStream::InstanceSize(len)));
+  obj->ptr()->length_ = len;
+  return obj;
 }