Stack-allocate block variables

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index cde5e7182df0cba24ed1147a4b503d62a9b0a9e9..1ccd48ee6a5fb280b2e6884dffca51440dc7f637 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -462,9 +462,12 @@ void AstGraphBuilder::VisitBlock(Block* stmt) {
     // Visit statements in the same scope, no declarations.
     VisitStatements(stmt->statements());
   } else {
-    const Operator* op = javascript()->CreateBlockContext();
-    Node* scope_info = jsgraph()->Constant(stmt->scope()->GetScopeInfo());
-    Node* context = NewNode(op, scope_info, GetFunctionClosure());
+    Node* context = nullptr;
+    if (stmt->scope()->ContextLocalCount() > 0) {
+      const Operator* op = javascript()->CreateBlockContext();
+      Node* scope_info = jsgraph()->Constant(stmt->scope()->GetScopeInfo());
+      context = NewNode(op, scope_info, GetFunctionClosure());
+    }
     ContextScope scope(this, stmt->scope(), context);
 
     // Visit declarations and statements in a block scope.