Revert of includes: Make ast.h not need isolate.h any more.

src/ast/ast-traversal-visitor.h

Index: src/ast/ast-traversal-visitor.h
diff --git a/src/ast/ast-traversal-visitor.h b/src/ast/ast-traversal-visitor.h
index 599c6d9c5c2945a7cc6b9e06ae5856386d340d6a..0f2976c4ca4f9e6b9b290ad761620c4881609b74 100644
--- a/src/ast/ast-traversal-visitor.h
+++ b/src/ast/ast-traversal-visitor.h
@@ -28,6 +28,7 @@
 template <class Subclass>
 class AstTraversalVisitor : public AstVisitor<Subclass> {
  public:
+  explicit AstTraversalVisitor(Isolate* isolate, AstNode* root = nullptr);
   explicit AstTraversalVisitor(uintptr_t stack_limit, AstNode* root = nullptr);
 
   void Run() {
@@ -87,6 +88,12 @@
     if (HasStackOverflow()) return; \
   } while (false)
 
+template <class Subclass>
+AstTraversalVisitor<Subclass>::AstTraversalVisitor(Isolate* isolate,
+                                                   AstNode* root)
+    : root_(root), depth_(0) {
+  InitializeAstVisitor(isolate);
+}
 
 template <class Subclass>
 AstTraversalVisitor<Subclass>::AstTraversalVisitor(uintptr_t stack_limit,