ES6: String(symbol) should work like symbol.toString

src/string.js

Index: src/string.js
diff --git a/src/string.js b/src/string.js
index ae65264d4a3ae2c29cc39add829dd45e51ccf0c3..1f14ec3dc69c09f1ca85bb0db3c73c364e0c175a 100644
--- a/src/string.js
+++ b/src/string.js
@@ -9,11 +9,12 @@
 // -------------------------------------------------------------------
 
 function StringConstructor(x) {
-  var value = %_ArgumentsLength() == 0 ? '' : TO_STRING_INLINE(x);
   if (%_IsConstructCall()) {
-    %_SetValueOf(this, value);
+    %_SetValueOf(this, %_ArgumentsLength() == 0 ? '' : TO_STRING_INLINE(x));
   } else {
-    return value;
+    if (%_ArgumentsLength() == 0) return '';

[rossberg, 2014/09/12 12:56:38]

We could avoid duplicating this case by pulling out

  if (%_ArgumentsLength() == 0) x = '';

+    if (IS_SYMBOL(x)) return %_CallFunction(x, SymbolToString);
+    return TO_STRING_INLINE(x);

[rossberg, 2014/09/12 12:56:38]

Nit: merge the returns into a ?:

   }
 }