Fix crash in inline cache: forgot to GC properly RawICData. Various cleanups.

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 4802)
+++ runtime/vm/object.h	(working copy)
@@ -3679,10 +3679,6 @@
     return raw_ptr()->target_name_;
   }
 
-  RawArray* ic_data() const {
-    return raw_ptr()->ic_data_;
-  }
-
   intptr_t num_args_tested() const {
     return raw_ptr()->num_args_tested_;
   }
@@ -3726,6 +3722,10 @@
                         intptr_t num_args_tested);
 
  private:
+  RawArray* ic_data() const {
+    return raw_ptr()->ic_data_;
+  }
+
   void set_function(const Function& value) const;
   void set_target_name(const String& value) const;
   void set_id(intptr_t value) const;