Ensure that reading more characters at the end of the buffer is not s…

…topped due to the buffer appearing being at the end with reading, rather we read till we get a -1. Streams can deliver less than requested size and hence the buffer looks like it it almost finished, but it is technically not.

src/main/java/org/htmlunit/cyberneko/HTMLScanner.java

@@ -2341,10 +2341,8 @@ protected String nextContent(final int len) throws IOException {
             for (nbRead = 0; nbRead < len; ++nbRead) {
                 // read() should not clear the buffer
                 if (fCurrentEntity.offset_ == fCurrentEntity.length_) {
-                    if (fCurrentEntity.length_ == fCurrentEntity.buffer_.length) {
-                        fCurrentEntity.load(fCurrentEntity.buffer_.length);
-                    }
-                    else { // everything was already loaded
+                    final int count = fCurrentEntity.load(fCurrentEntity.offset_);
+                    if (count == -1) {
                         break;
                     }
                 }