Add script context with context-allocated "const this"

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 810a8b92210d4bb2389d024490c65b0b88e22eb1..672ff51aa3f2bbcd74138f99fad982f0741d338a 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -10197,12 +10197,14 @@ void HOptimizedGraphBuilder::VisitDelete(UnaryOperation* expr) {
     if (var->IsUnallocated()) {
       Bailout(kDeleteWithGlobalVariable);
     } else if (var->IsStackAllocated() || var->IsContextSlot()) {
-      // Result of deleting non-global variables is false.  'this' is not
-      // really a variable, though we implement it as one.  The
-      // subexpression does not have side effects.
-      HValue* value = var->is_this()
-          ? graph()->GetConstantTrue()
-          : graph()->GetConstantFalse();
+      // Result of deleting non-global variables is false.  'this' is not really
+      // a variable, though we implement it as one.  The subexpression does not
+      // have side effects.  (It could be that the "this" variable has DYNAMIC
+      // resolution though so we haven't been able to map it to Variable::THIS,
+      // but regardless if its name is "this" then it is "this".)
+      bool is_this = *var->name() == *isolate()->factory()->this_string();
+      HValue* value =
+          is_this ? graph()->GetConstantTrue() : graph()->GetConstantFalse();
       return ast_context()->ReturnValue(value);
     } else {
       Bailout(kDeleteWithNonGlobalVariable);