[wasm][asm.js] Utf8 encode exported function names.

BUG=672047
R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2555203002
Cr-Commit-Position: refs/heads/master@{#41576}

src/asmjs/asm-wasm-builder.cc

@@ -714,11 +714,13 @@ class AsmWasmBuilderImpl final : public AstVisitor<AsmWasmBuilderImpl> {
       Literal* name = prop->key()->AsLiteral();
       DCHECK_NOT_NULL(name);
       DCHECK(name->IsPropertyName());
-      const AstRawString* raw_name = name->AsRawPropertyName();
+      Handle<String> function_name = name->AsPropertyName();
+      int length;
+      std::unique_ptr<char[]> utf8 = function_name->ToCString(
+          DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &length);
       if (var->is_function()) {
         WasmFunctionBuilder* function = LookupOrInsertFunction(var);
-        function->ExportAs({reinterpret_cast<const char*>(raw_name->raw_data()),
-                            raw_name->length()});
+        function->ExportAs({utf8.get(), length});
       }
     }
   }

test/mjsunit/wasm/asm-wasm.js

@@ -1497,6 +1497,21 @@ assertWasm(-34359738370.75, TestNegativeDouble);
 })();
 
 
+(function TestUnicodeExportKey() {
+  function Module() {
+    "use asm";
+    function func() {
+      return 42;
+    }
+    return {"\u00d1\u00e6": func};
+  }
+
+  var m = Module(stdlib);
+  assertEquals(42, m.Ñæ());
+  assertValidAsm(Module);
+})();
+
+
 function TestAndIntAndHeapValue(stdlib, foreign, buffer) {
   "use asm";
   var HEAP32 = new stdlib.Int32Array(buffer);