Fix the semantics of delete on parameters.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index b9bd9599760373b90bf4fc21a4823902ad553684..e357450f335e1029e516bb9ef803355ff7a29450 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -3053,26 +3053,30 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         // Result of deleting non-global, non-dynamic variables is false.
         // The subexpression does not have side effects.
         context()->Plug(false);
-      } else {
-        // Property or variable reference.  Call the delete builtin with
-        // object and property name as arguments.
-        if (prop != NULL) {
+      } else if (prop != NULL) {
+        if (prop->is_synthetic()) {
+          // Result of deleting parameters is false, even when they rewrite
+          // to accesses on the arguments object.
+          context()->Plug(false);
+        } else {
           VisitForStackValue(prop->obj());
           VisitForStackValue(prop->key());
           __ InvokeBuiltin(Builtins::DELETE, CALL_JS);
-        } else if (var->is_global()) {
-          __ ldr(r1, GlobalObjectOperand());
-          __ mov(r0, Operand(var->name()));
-          __ Push(r1, r0);
-          __ InvokeBuiltin(Builtins::DELETE, CALL_JS);
-        } else {
-          // Non-global variable.  Call the runtime to delete from the
-          // context where the variable was introduced.
-          __ push(context_register());
-          __ mov(r2, Operand(var->name()));
-          __ push(r2);
-          __ CallRuntime(Runtime::kDeleteContextSlot, 2);
+          context()->Plug(r0);
         }
+      } else if (var->is_global()) {
+        __ ldr(r1, GlobalObjectOperand());
+        __ mov(r0, Operand(var->name()));
+        __ Push(r1, r0);
+        __ InvokeBuiltin(Builtins::DELETE, CALL_JS);
+        context()->Plug(r0);
+      } else {
+        // Non-global variable.  Call the runtime to try to delete from the
+        // context where the variable was introduced.
+        __ push(context_register());
+        __ mov(r2, Operand(var->name()));
+        __ push(r2);
+        __ CallRuntime(Runtime::kDeleteContextSlot, 2);
         context()->Plug(r0);
       }
       break;