Implement proper scoping for "this" in arrow functions

src/arm64/lithium-codegen-arm64.cc

Index: src/arm64/lithium-codegen-arm64.cc
diff --git a/src/arm64/lithium-codegen-arm64.cc b/src/arm64/lithium-codegen-arm64.cc
index 3b7c29645068824c6887fe51bf615bd0c34f0922..3ef0e78b27cf60ff949d9ccf88a3afa539b02997 100644
--- a/src/arm64/lithium-codegen-arm64.cc
+++ b/src/arm64/lithium-codegen-arm64.cc
@@ -642,7 +642,8 @@ bool LCodeGen::GeneratePrologue() {
     // object).
     if (info_->this_has_uses() &&
         info_->strict_mode() == SLOPPY &&
-        !info_->is_native()) {
+        !info_->is_native() &&
+        info_->scope()->has_this_declaration()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kXRegSize;
       __ Peek(x10, receiver_offset);
@@ -700,8 +701,9 @@ bool LCodeGen::GeneratePrologue() {
     __ Str(x0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    for (int i = 0; i < num_parameters; i++) {
-      Variable* var = scope()->parameter(i);
+    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);
       if (var->IsContextSlot()) {
         Register value = x0;
         Register scratch = x3;