Eliminate all Closure compiler warnings.

Create diff class in JS that looks the same as an array-based tuple.

Author: Neil Fraser

objectivec/DiffMatchPatch.m

@@ -202,7 +202,7 @@ - (id)copyWithZone:(NSZone *)zone
 /**
  * Emulate GNU diff's format.
  * Header: @@ -382,8 +481,9 @@
- * Indicies are printed as 1-based, not 0-based.
+ * Indices are printed as 1-based, not 0-based.
  * @return The GNU diff NSString.
  */
 - (NSString *)description