Make line-starts 32-bits TypedData instead of Array of smis.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index be420b3561dc20fc4ca1248e6817aec8d7632d31..715ba025f5311c969d07936017300d612643c7e4 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -3683,7 +3683,7 @@ class Script : public Object {
     return raw_ptr()->tokens_;
   }
 
-  void set_line_starts(const Array& value) const;
+  void set_line_starts(const TypedData& value) const;
 
   void set_debug_positions(const Array& value) const;
 
@@ -3741,7 +3741,7 @@ class Script : public Object {
   void set_kind(RawScript::Kind value) const;
   void set_load_timestamp(int64_t value) const;
   void set_tokens(const TokenStream& value) const;
-  RawArray* line_starts() const;
+  RawTypedData* line_starts() const;
   RawArray* debug_positions() const;
 
   static RawScript* New();