Send the block data compressed using the given Huffman trees
function compress_block(ltree, dtree) {
			var dist; // distance of matched string
			var lc; // match length or unmatched char (if dist === 0)
			var lx = 0; // running index in l_buf
			var code; // the code to send
			var extra; // number of extra bits to send

			if (last_lit !== 0) {
				do {
					dist = ((that.pending_buf[d_buf + lx * 2] << 8) & 0xff00) | (that.pending_buf[d_buf + lx * 2 + 1] & 0xff);
					lc = (that.pending_buf[l_buf + lx]) & 0xff;
					lx++;

					if (dist === 0) {
						send_code(lc, ltree); // send a literal byte
					} else {
						// Here, lc is the match length - MIN_MATCH
						code = Tree._length_code[lc];

						send_code(code + LITERALS + 1, ltree); // send the length
						// code
						extra = Tree.extra_lbits[code];
						if (extra !== 0) {
							lc -= Tree.base_length[code];
							send_bits(lc, extra); // send the extra length bits
						}
						dist--; // dist is now the match distance - 1
						code = Tree.d_code(dist);

						send_code(code, dtree); // send the distance code
						extra = Tree.extra_dbits[code];
						if (extra !== 0) {
							dist -= Tree.base_dist[code];
							send_bits(dist, extra); // send the extra distance bits
						}
					} // literal or match pair ?

					// Check that the overlay between pending_buf and d_buf+l_buf is
					// ok:
				} while (lx < last_lit);
			}

			send_code(END_BLOCK, ltree);
			last_eob_len = ltree[END_BLOCK * 2 + 1];
		}