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

src/arm64/assembler-arm64-inl.h

Index: src/arm64/assembler-arm64-inl.h
diff --git a/src/arm64/assembler-arm64-inl.h b/src/arm64/assembler-arm64-inl.h
index 3fbb09147b19e6880eac71554c4f611c2d752ffd..f02207f5497d533949bd6b85d511b0b771f41ec5 100644
--- a/src/arm64/assembler-arm64-inl.h
+++ b/src/arm64/assembler-arm64-inl.h
@@ -665,7 +665,7 @@ void Assembler::set_target_address_at(Address pc, Address constant_pool,
   Memory::Address_at(target_pointer_address_at(pc)) = target;
   // Intuitively, we would think it is necessary to always flush the
   // instruction cache after patching a target address in the code as follows:
-  //   CpuFeatures::FlushICache(pc, sizeof(target));
+  //   Assembler::FlushICacheWithoutIsolate(pc, sizeof(target));
   // However, on ARM, an instruction is actually patched in the case of
   // embedded constants of the form:
   // ldr   ip, [pc, #...]