Bug 513681 - part 1 - fix a few warnings.r=joe,a=blocker

modules/libpr0n/decoders/png/nsPNGDecoder.cpp

@@ -776,7 +776,7 @@ row_callback(png_structp png_ptr, png_bytep new_row,
   if (decoder->mFrameIsHidden)
     return;
 
-  if (row_num >= decoder->mFrameRect.height)
+  if (row_num >= (png_uint_32) decoder->mFrameRect.height)
     return;
 
   if (new_row) {

modules/libpr0n/src/imgRequest.cpp

@@ -960,7 +960,7 @@ NS_IMETHODIMP imgRequest::OnDataAvailable(nsIRequest *aRequest, nsISupports *ctx
 
     /* now we have mimetype, so we can infer the image type that we want */
     imageType = mContentType.EqualsLiteral(SVG_MIMETYPE) ?
-      imgIContainer::TYPE_VECTOR : imgIContainer::TYPE_RASTER;
+      (PRUint16) imgIContainer::TYPE_VECTOR : (PRUint16) imgIContainer::TYPE_RASTER;
 
     /* set our mimetype as a property */
     nsCOMPtr<nsISupportsCString> contentType(do_CreateInstance("@mozilla.org/supports-cstring;1"));