Fix three ~Isolate() related memory leaks

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index eae812bcd94bdc35c4d48a497a17375fc332fd5f..16a6cd2de0067d517777c3180c47c2f64230df9e 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1335,6 +1335,7 @@ void Isolate::ThreadDataTable::Remove(PerIsolateThreadData* data) {
   if (list_ == data) list_ = data->next_;
   if (data->next_ != NULL) data->next_->prev_ = data->prev_;
   if (data->prev_ != NULL) data->prev_->next_ = data->next_;
+  delete data;
 }
 
 
@@ -1536,6 +1537,9 @@ Isolate::~Isolate() {
   // Has to be called while counters_ are still alive.
   zone_.DeleteKeptSegment();
 
+  delete assembler_spare_buffer_;
+  assembler_spare_buffer_ = NULL;
+
   delete unicode_cache_;
   unicode_cache_ = NULL;