Make FlushICache part of Assembler(Base) and take Isolate as parameter.

test/cctest/test-code-stubs-arm64.cc

Index: test/cctest/test-code-stubs-arm64.cc
diff --git a/test/cctest/test-code-stubs-arm64.cc b/test/cctest/test-code-stubs-arm64.cc
index 8b38b9660099a6b9e8059c6fbaecd69437353013..c9fddbeacf024ad7729b3ecd192147e5626b17fc 100644
--- a/test/cctest/test-code-stubs-arm64.cc
+++ b/test/cctest/test-code-stubs-arm64.cc
@@ -122,7 +122,7 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
 
   CodeDesc desc;
   masm.GetCode(&desc);
-  CpuFeatures::FlushICache(buffer, actual_size);
+  Assembler::FlushICacheWithoutIsolate(buffer, actual_size);
   return (reinterpret_cast<ConvertDToIFunc>(
       reinterpret_cast<intptr_t>(buffer)));
 }