[intrinsic] Drop the %_ValueOf intrinsic.

src/debug/mirrors.js

Index: src/debug/mirrors.js
diff --git a/src/debug/mirrors.js b/src/debug/mirrors.js
index 2e7920d9b4ff4d9a27f28944f7d5d128eac8d683..adf5133da5e9f7961d8017f5c634f612de498659 100644
--- a/src/debug/mirrors.js
+++ b/src/debug/mirrors.js
@@ -19,7 +19,6 @@ var promiseStateSymbol = utils.ImportNow("promise_state_symbol");
 var promiseResultSymbol = utils.ImportNow("promise_result_symbol");
 var SetIteratorNext;
 var SetValues;
-var SymbolToString;
 
 utils.Import(function(from) {
   ErrorToString = from.ErrorToString;
@@ -28,7 +27,6 @@ utils.Import(function(from) {
   MapIteratorNext = from.MapIteratorNext;
   SetIteratorNext = from.SetIteratorNext;
   SetValues = from.SetValues;
-  SymbolToString = from.SymbolToString;
 });
 
 // ----------------------------------------------------------------------------
@@ -686,12 +684,12 @@ inherits(SymbolMirror, ValueMirror);
 
 
 SymbolMirror.prototype.description = function() {
-  return %SymbolDescription(%_ValueOf(this.value_));
+  return %SymbolDescription(%ValueOf(this.value_));
 }
 
 
 SymbolMirror.prototype.toText = function() {
-  return %_Call(SymbolToString, this.value_);
+  return %SymbolDescriptiveString(%ValueOf(this.value_));
 }