Debugger: add ability to set script source from within OnBeforeCompile.

src/mirror-debugger.js

Index: src/mirror-debugger.js
diff --git a/src/mirror-debugger.js b/src/mirror-debugger.js
index 168a12d3aa80d5b214c18e3a16ead37ea0f41629..c43dd228ec9d12c73a0d66a4102477649f85862f 100644
--- a/src/mirror-debugger.js
+++ b/src/mirror-debugger.js
@@ -1832,6 +1832,11 @@ ScriptMirror.prototype.source = function() {
 };
 
 
+ScriptMirror.prototype.setSource = function(source) {
+  %DebugSetScriptSource(this.script_, source);
+};
+
+
 ScriptMirror.prototype.lineOffset = function() {
   return this.script_.line_offset;
 };