Add kernel_offset to all expressions; Make KernelConstMapKeyEqualsTraits use kernel_offset

runtime/vm/kernel.h

Index: runtime/vm/kernel.h
diff --git a/runtime/vm/kernel.h b/runtime/vm/kernel.h
index a4076961985f0ad0c517611c75cf11b8676144a5..539f73529c7c87896dcb330cd38f2b809a2c92a5 100644
--- a/runtime/vm/kernel.h
+++ b/runtime/vm/kernel.h
@@ -434,7 +434,7 @@ class TreeNode : public Node {
 
   virtual void AcceptVisitor(Visitor* visitor);
   virtual void AcceptTreeVisitor(TreeVisitor* visitor) = 0;
-  intptr_t kernel_offset() { return kernel_offset_; }
+  intptr_t kernel_offset() const { return kernel_offset_; }
 
  protected:
   TreeNode() : kernel_offset_(-1) {}
@@ -1348,6 +1348,8 @@ class StaticInvocation : public Expression {
   static StaticInvocation* ReadFrom(Reader* reader, bool is_const);
   ~StaticInvocation();
 
+  DEFINE_CASTING_OPERATIONS(StaticInvocation);
+
   virtual void AcceptExpressionVisitor(ExpressionVisitor* visitor);
   virtual void VisitChildren(Visitor* visitor);