Fix Issue 1320: LiveEdit: text differencer fails with out of memory on large files

src/liveedit-debugger.js

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 970 matching lines @@
   function SetScriptSource(script, new_source, preview_only, change_log) {
     var old_source = script.source;
     var diff = CompareStrings(old_source, new_source);
     return ApplyPatchMultiChunk(script, diff, new_source, preview_only,
         change_log);
   }
   // Function is public.
   this.SetScriptSource = SetScriptSource;
 
   function CompareStrings(s1, s2) {
-    return %LiveEditCompareStrings(s1, s2);
+    try {
+      return %LiveEditCompareStrings(s1, s2);
+    } catch (e) {
+      throw new Failure("Failed to calculate text difference: " + String(e));
+    }
   }
 
   // Applies the change to the script.
   // The change is always a substring (change_pos, change_pos + change_len)
   // being replaced with a completely different string new_str.
   // This API is a legacy and is obsolete.
   //
   // @param {Script} script that is being changed
   // @param {Array} change_log a list that collects engineer-readable
   //     description of what happened.
@@ skipping 71 matching lines @@
   }
 
 
   // Functions are public for tests.
   this.TestApi = {
     PosTranslator: PosTranslator,
     CompareStrings: CompareStrings,
     ApplySingleChunkPatch: ApplySingleChunkPatch
   }
 }