Revert of Resolve references to "this" the same way as normal variables

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index ba0087430e718707f8f50afb0f1ccc3ad3754850..51b85fc7f9489b2e8077f5b635e0fc23f899abed 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -129,8 +129,8 @@
 
     // Sloppy mode functions need to replace the receiver with the global proxy
     // when called as functions (without an explicit receiver object).
-    if (is_sloppy(info()->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
+        !info_->is_native()) {
       Label ok;
       StackArgumentsAccessor args(rsp, scope()->num_parameters());
       __ movp(rcx, args.GetReceiverOperand());
@@ -213,9 +213,8 @@
 
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
-    for (int i = first_parameter; i < num_parameters; i++) {
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
+    for (int i = 0; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;