runtime: Minor cleanup and extra comments around interpreter

Change-Id: I24c0b261de8cf737babd9d01bf679482d48c8bc9
diff --git a/runtime/mirror/string.h b/runtime/mirror/string.h
index a8f16d7..af06385 100644
--- a/runtime/mirror/string.h
+++ b/runtime/mirror/string.h
@@ -95,7 +95,7 @@
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   template <bool kIsInstrumented>
-  ALWAYS_INLINE static String* AllocFromCharArray(Thread* self, int32_t array_length,
+  ALWAYS_INLINE static String* AllocFromCharArray(Thread* self, int32_t count,
                                                   Handle<CharArray> array, int32_t offset,
                                                   gc::AllocatorType allocator_type)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);