[wasm] Only SNPrintF the function index if a name was not supplied.

src/wasm/wasm-objects.cc

Index: src/wasm/wasm-objects.cc
diff --git a/src/wasm/wasm-objects.cc b/src/wasm/wasm-objects.cc
index f2d614e0f7e784f0f61bab598f6bd6c8e77f5b75..1e9fc8c9c7d4c3763265699a836b1428d470c145 100644
--- a/src/wasm/wasm-objects.cc
+++ b/src/wasm/wasm-objects.cc
@@ -312,10 +312,10 @@ Handle<WasmExportedFunction> WasmExportedFunction::New(
     Isolate* isolate, Handle<WasmInstanceObject> instance,
     MaybeHandle<String> maybe_name, int func_index, int arity,
     Handle<Code> export_wrapper) {
-  ScopedVector<char> buffer(16);
-  int length = SNPrintF(buffer, "%d", func_index);
   Handle<String> name;
   if (maybe_name.is_null()) {
+    ScopedVector<char> buffer(16);

[Clemens Hammacher, 2016/12/20 11:25:54]

We should make this an EmbeddedVector<char, 16>, such that it's completely
stack-allocated.
There are probably many more opportunities for this change.

+    int length = SNPrintF(buffer, "%d", func_index);
     name = isolate->factory()
                ->NewStringFromAscii(
                    Vector<const char>::cast(buffer.SubVector(0, length)))