Bump the C stack pointer when building Dart frames to maintain the ARM64 ABI requirements without g…

runtime/vm/assembler_arm64.h

Index: runtime/vm/assembler_arm64.h
diff --git a/runtime/vm/assembler_arm64.h b/runtime/vm/assembler_arm64.h
index 735e07e7ff2740d5651f1c50bb54bd3bb1a94c6a..8080ab8b6fe9c7e480511ef97615437792847b9f 100644
--- a/runtime/vm/assembler_arm64.h
+++ b/runtime/vm/assembler_arm64.h
@@ -1349,18 +1349,12 @@ class Assembler : public ValueObject {
                            Register scratch2,
                            Label* miss);
 
+  void SetupDartSP();
+  void RestoreCSP();
+
   void EnterFrame(intptr_t frame_size);
   void LeaveFrame();
 
-  // When entering Dart code from C++, we copy the system stack pointer (CSP)
-  // to the Dart stack pointer (SP), and reserve a little space for the stack
-  // to grow.
-  void SetupDartSP(intptr_t reserved_space) {
-    ASSERT(Utils::IsAligned(reserved_space, 16));
-    mov(SP, CSP);
-    sub(CSP, CSP, Operand(reserved_space));
-  }
-
   void CheckCodePointer();
   void RestoreCodePointer();