[wasm] Avoid double-serializing the wire bytes

test/mjsunit/wasm/direct-import-call.js

+// 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.
+
+// Flags: --expose-wasm
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+(function testCallImport() {
+    var builder = new WasmModuleBuilder();
+
+    var sig_index = builder.addType(kSig_d_dd);
+    builder.addImport("func", sig_index);
+    builder.addFunction("main", sig_index)
+        .addBody([
+            kExprGetLocal, 0,            // --
+            kExprGetLocal, 1,            // --
+            kExprCallFunction, 0])         // --
+        .exportAs("main");
+
+    var main = builder.instantiate({func: experimentalDoubleAdder}).exports.main;
+    assertEquals(3.8, main(1.5, 2.3));
+})();