[wasm] Refactor import handling for 0xC.

test/mjsunit/wasm/test-wasm-module-builder.js

 // Copyright 2016 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');
 
 var debug = true;
 
 (function BasicTest() {
     var module = new WasmModuleBuilder();
     module.addMemory(1, 2, false);
-    module.addFunction("foo", kSig_i)
+    module.addFunction("foo", kSig_i_v)
         .addBody([kExprI8Const, 11])
         .exportAs("blarg");
 
     var buffer = module.toBuffer(debug);
     var instance = Wasm.instantiateModule(buffer);
     assertEquals(11, instance.exports.blarg());
 })();
 
 (function ImportTest() {
     var module = new WasmModuleBuilder();
@@ skipping 83 matching lines @@
 
     var buffer = module.toBuffer(debug);
     var instance = Wasm.instantiateModule(buffer);
     assertEquals(151587081, instance.exports.load(0));
 })();
 
 
 (function BasicTestWithUint8Array() {
     var module = new WasmModuleBuilder();
     module.addMemory(1, 2, false);
-    module.addFunction("foo", kSig_i)
+    module.addFunction("foo", kSig_i_v)
         .addBody([kExprI8Const, 17])
         .exportAs("blarg");
 
     var buffer = module.toBuffer(debug);
     var array = new Uint8Array(buffer);
     var instance = Wasm.instantiateModule(array);
     assertEquals(17, instance.exports.blarg());
 
     var kPad = 5;
     var buffer2 = new ArrayBuffer(kPad + buffer.byteLength + kPad);
@@ skipping 14 matching lines @@
     var index = module.addImportWithModule("mod", "print", makeSig_v_x(kAstI32));
     module.addFunction("foo", kSig_v_v)
         .addBody([kExprI8Const, 19, kExprCallFunction, index])
         .exportAs("main");
 
     var buffer = module.toBuffer(debug);
     var instance = Wasm.instantiateModule(buffer, {mod: {print: print}});
     print("should print 19! ");
     instance.exports.main();
 })();