Make the values of Platform.executable and Platform.script available to all isolates

runtime/bin/platform.h

Index: runtime/bin/platform.h
diff --git a/runtime/bin/platform.h b/runtime/bin/platform.h
index 54412bac3209bfcb8a0e4562770f77b05c3ac7e3..dd195c32924042268b5768efe2d10f3d7e486950 100644
--- a/runtime/bin/platform.h
+++ b/runtime/bin/platform.h
@@ -34,7 +34,17 @@ class Platform {
   static char** Environment(intptr_t* count);
   static void FreeEnvironment(char** env, intptr_t count);
 
+  // Stores and gets the executable name.
+  static void SetExecutableName(const char* executable_name) {
+    executable_name_ = executable_name;
+  }
+  static const char* GetExecutableName() {
+    return executable_name_;
+  }
+
  private:
+  static const char* executable_name_;
+
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Platform);
 };