ARM64: Remove some unused variables.

src/arm64/builtins-arm64.cc

Index: src/arm64/builtins-arm64.cc
diff --git a/src/arm64/builtins-arm64.cc b/src/arm64/builtins-arm64.cc
index a638d8dfbdc3543e5b54022548eb338f0e47771c..dfb59c0504dacb1f3ffa5d7a616d6665bb8581db 100644
--- a/src/arm64/builtins-arm64.cc
+++ b/src/arm64/builtins-arm64.cc
@@ -1327,7 +1327,6 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
 static void Generate_CheckStackOverflow(MacroAssembler* masm,
                                         const int calleeOffset) {
   Register argc = x0;
-  Register receiver = x14;
   Register function = x15;
 
   // Check the stack for overflow.
@@ -1531,7 +1530,6 @@ static void Generate_ConstructHelper(MacroAssembler* masm) {
     // Is x11 safe to use?
     Register newTarget = x11;
     Register args = x12;
-    Register receiver = x14;
     Register function = x15;
 
     // If newTarget is not supplied, set it to constructor