Expose a lower bound of malloc'd memory via heap statistics

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

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "test/unittests/test-utils.h"
 
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-opcodes.h"
 
@@ skipping 761 matching lines @@
 
   EXPECT_FAILURE(data);
 }
 
 
 class WasmSignatureDecodeTest : public TestWithZone {};
 
 
 TEST_F(WasmSignatureDecodeTest, Ok_v_v) {
   static const byte data[] = {0, 0};
-  Zone zone;
+  ZoneForTesting zone;
   FunctionSig* sig =
       DecodeWasmSignatureForTesting(&zone, data, data + arraysize(data));
 
   EXPECT_TRUE(sig != nullptr);
   EXPECT_EQ(0, sig->parameter_count());
   EXPECT_EQ(0, sig->return_count());
 }
 
 
 TEST_F(WasmSignatureDecodeTest, Ok_t_v) {
@@ skipping 576 matching lines @@
       NO_LOCAL_NAMES,  // --
       FOO_STRING,
       NO_LOCAL_NAMES,  // --
   };
   EXPECT_VERIFIES(data);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8