Moved zones and zone related stuff in its own directory.

test/unittests/wasm/module-decoder-unittest.cc

Index: test/unittests/wasm/module-decoder-unittest.cc
diff --git a/test/unittests/wasm/module-decoder-unittest.cc b/test/unittests/wasm/module-decoder-unittest.cc
index 7e8f86eead1a0d31bdf1414a3ccb95dbb06b411d..3c235adf1b469e1077eb52dd56e817e8f444e381 100644
--- a/test/unittests/wasm/module-decoder-unittest.cc
+++ b/test/unittests/wasm/module-decoder-unittest.cc
@@ -604,7 +604,7 @@ class WasmSignatureDecodeTest : public TestWithZone {};
 
 TEST_F(WasmSignatureDecodeTest, Ok_v_v) {
   static const byte data[] = {SIG_ENTRY_v_v};
-  base::AccountingAllocator allocator;
+  v8::internal::AccountingAllocator allocator;
   Zone zone(&allocator);
   FunctionSig* sig =
       DecodeWasmSignatureForTesting(&zone, data, data + arraysize(data));