Fixes issue mozilla#6071

Corrects readBlockTiff() case for 1-bit depth TIFF images incorporated in
the PDF.

Corrected sintaxe according to style guide.

src/core/stream.js

@@ -740,14 +740,15 @@ var PredictorStream = (function PredictorStreamClosure() {
     var i;
 
     if (bits === 1) {
+      var complement = 0;
+      var bitOrder = 0;
       for (i = 0; i < rowBytes; ++i) {
-        var c = rawBytes[i];
-        inbuf = (inbuf << 8) | c;
-        // bitwise addition is exclusive or
-        // first shift inbuf and then add
-        buffer[pos++] = (c ^ (inbuf >> colors)) & 0xFF;
-        // truncate inbuf (assumes colors < 16)
-        inbuf &= 0xFFFF;
+        inbuf = (inbuf << 8) | (rawBytes[i] & 0xFF);
+        for (bitOrder = 7; bitOrder >= 0; --bitOrder) {
+          complement = (complement + (inbuf >> bitOrder)) & 0x1;
+          outbuf = (outbuf << 1) | complement;
+        }
+        buffer[pos++] = (outbuf & 0xFF);
       }
     } else if (bits === 8) {
       for (i = 0; i < colors; ++i) {