Fix for Clusterfuzz issue 343928.

src/contexts.h

Index: src/contexts.h
diff --git a/src/contexts.h b/src/contexts.h
index b2e0661a348557a864150c67fa78985b53f18452..d15ef867686504ab095c240fb5c128723cd9e806 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -226,8 +226,11 @@ enum BindingFlags {
 // In addition, function contexts may have statically allocated context slots
 // to store local variables/functions that are accessed from inner functions
 // (via static context addresses) or through 'eval' (dynamic context lookups).
-// Finally, the native context contains additional slots for fast access to
-// native properties.
+// The native context contains additional slots for fast access to native
+// properties.
+//
+// Finally, with Harmony scoping, the JSFunction representing a top level
+// script will have the GlobalContext rather than a FunctionContext.
 
 class Context: public FixedArray {
  public: