[Isolates] Fix compilation of Chrome on Linux.

src/preparser-api.cc

Index: src/preparser-api.cc
===================================================================
--- src/preparser-api.cc	(revision 7185)
+++ src/preparser-api.cc	(working copy)
@@ -161,6 +161,9 @@
 
 class StandAloneJavaScriptScanner : public JavaScriptScanner {
  public:
+  StandAloneJavaScriptScanner()
+    : JavaScriptScanner(Isolate::Current()) { }
+
   void Initialize(UC16CharacterStream* source) {
     source_ = source;
     Init();