backout c7e523e3d339 (bug 1083373 part 2) for Android debug build warning, treated as error

media/gmp-clearkey/0.1/ClearKeyUtils.cpp

@@ -10,8 +10,6 @@
 #include <vector>
 
 #include "ClearKeyUtils.h"
-#include "mozilla/ArrayUtils.h"
-#include "mozilla/Assertions.h"
 #include "mozilla/Endian.h"
 #include "mozilla/NullPtr.h"
 #include "openaes/oaes_lib.h"
@@ -108,12 +106,7 @@ EncodeBase64Web(vector<uint8_t> aBinary, string& aEncoded)
     out[i] += (*data >> (shift + 2)) & sMask;
     shift = (shift + 2) % 8;
 
-    auto idx = out[i];
-    MOZ_ASSERT(idx >= 0 &&
-               static_cast<size_t>(idx) < MOZ_ARRAY_LENGTH(sAlphabet),
-               "out of bounds index for 'sAlphabet'");
-    // Cast idx to size_t to pacify clang 'Wchar-subscripts' warning:
-    out[i] = sAlphabet[static_cast<size_t>(idx)];
+    out[i] = sAlphabet[out[i]];
   }
 
   return true;