Remove inessential functions from the JS Script class

src/debug/mirrors.js

Index: src/debug/mirrors.js
diff --git a/src/debug/mirrors.js b/src/debug/mirrors.js
index 7014c97d1338c103844eec9688d5d98ac708ac78..1aaa22aa7ef73faba17ed5960fa915ec1cb2444f 100644
--- a/src/debug/mirrors.js
+++ b/src/debug/mirrors.js
@@ -2356,7 +2356,7 @@ ScriptMirror.prototype.compilationType = function() {
 
 
 ScriptMirror.prototype.lineCount = function() {
-  return this.script_.lineCount();
+  return %ScriptLineCount(this.script_);
 };
 
 
@@ -2366,11 +2366,6 @@ ScriptMirror.prototype.locationFromPosition = function(
 };
 
 
-ScriptMirror.prototype.sourceSlice = function (opt_from_line, opt_to_line) {
-  return this.script_.sourceSlice(opt_from_line, opt_to_line);
-};
-
-
 ScriptMirror.prototype.context = function() {
   return this.context_;
 };