Revert b4c61130324455bfd42095b01fa14ac901e441f1

Was causing more trouble than it solved.  We use unsigned for indexing,
and it's not helpful to allow that wrapping to negative integers on
32bit machines.  The only way we could work around it would have been
by accepting int64_t arg, but that's overkill.

Ignore the MSVC 2008 build issue.  We don't support that compiler.
diff --git a/src/hb-open-type.hh b/src/hb-open-type.hh
index bae73da..c77c25f 100644
--- a/src/hb-open-type.hh
+++ b/src/hb-open-type.hh
@@ -339,25 +339,16 @@
 
   HB_NO_CREATE_COPY_ASSIGN_TEMPLATE (UnsizedArrayOf, Type);
 
-  /* Unlikely other places, use "ssize_t i" instead of "unsigned int i" for our
-   * indexing operator.  For three reasons:
-   * 1. For UnsizedArrayOf, it's not totally unimaginable to want to look
-   *    at items before the start of current array.
-   * 2. Use the largest type, to help detect overflows.
-   * 3. Fixes MSVC 2008 "overloads have similar conversions" issue with the
-   *    built-in operator [] that takes int, in expressions like sizeof (array[0])).
-   *    I suppose I could fix that by replacing 0 with 0u, but like this fix
-   *    more now. */
-  inline const Type& operator [] (ssize_t i) const
+  inline const Type& operator [] (unsigned int i) const
   {
     const Type *p = &arrayZ[i];
-    if (unlikely ((0 <= i) != (arrayZ <= p))) return Null (Type); /* Over/under-flowed. */
+    if (unlikely (p < arrayZ)) return Null (Type); /* Overflowed. */
     return *p;
   }
-  inline Type& operator [] (ssize_t i)
+  inline Type& operator [] (unsigned int i)
   {
     const Type *p = &arrayZ[i];
-    if (unlikely ((0 <= i) != (arrayZ <= p))) return Crap (Type); /* Over/under-flowed. */
+    if (unlikely (p < arrayZ)) return Crap (Type); /* Overflowed. */
     return *p;
   }