[wasm] Clean up test case

src/js/messages.js

Index: src/js/messages.js
diff --git a/src/js/messages.js b/src/js/messages.js
index 2ff2dd052baaad0256d9a71d6a82c0d811548a66..1e91d28e63dcb2b244e0e16f9671e44058e34a56 100644
--- a/src/js/messages.js
+++ b/src/js/messages.js
@@ -632,9 +632,10 @@ function CallSiteGetFunctionName() {
   CheckCallSite(this, "getFunctionName");
   if (HAS_PRIVATE(this, callSiteWasmObjectSymbol)) {
     var wasm = GET_PRIVATE(this, callSiteWasmObjectSymbol);
-    var func_index = GET_PRIVATE(this, callSiteWasmFunctionIndexSymbol);
     if (IS_UNDEFINED(wasm)) return "<WASM>";
-    return %WasmGetFunctionName(wasm, func_index);
+    var func_index = GET_PRIVATE(this, callSiteWasmFunctionIndexSymbol);
+    var func_name = %WasmGetFunctionName(wasm, func_index);
+    return func_name ? func_name : "<WASM>";

[Yang, 2016/05/09 05:34:55]

Can we do a IS_UNDEFINED check if we only expect undefined or strings?

[clemensh, 2016/05/09 07:38:46]

Unfortunately not. At least not without further changes in the way function
names are stored inside the wasm modules. It does not distinguish currently
between "no name" and "empty name". So we always get an empty string if no name
was set, and only get undefined if e.g. the string is no valid UTF-8.

[Yang, 2016/05/11 05:49:41]

I see. Can we hide this logic inside %WasmGetFunctionName? I'd like to avoid
implicit conversions, and it should be the job of the wasm part of V8 to deliver
the appropriate name.

   }
   return %CallSiteGetFunctionNameRT(this);
 }