Fix an assert to check the maximum compressed size of each MSZIP block

The maximum compressed size of each MSZIP block is 32k + 12 bytes.
So that means the size can be 32k + 12 bytes.
However, the assert checks as follows.

assert compressed_size < chunk_size + 12

Reference : https://msdn.microsoft.com/en-us/library/ee178063(v=exchg.80).aspx

Bug: None
Change-Id: I0d991be2909f4447144fccad83155c5967382557
Reviewed-on: https://chromium-review.googlesource.com/1074768
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567243}

AUTHORS

@@ -591,6 +591,7 @@ Mohammed Wajahat Ali Siddiqui <wajahat.s@samsung.com>
 Mohan Reddy <mohan.reddy@samsung.com>
 Mohit Bhalla <bhallam@amazon.com>
 Mrunal Kapade <mrunal.kapade@intel.com>
+Myeongjin Cho <myeongjin.cho@navercorp.com>
 Myles C. Maxfield <mymax@amazon.com>
 Myung-jong Kim <mjkim610@gmail.com>
 Nagarajan Narayanan <nagarajan.n@samsung.com>

chrome/tools/build/win/makecab.py

@@ -176,7 +176,7 @@ def WriteCab(output_file, input_file, cab_stored_filename, input_size,
     # last block in a folder may be smaller. A two-byte MSZIP signature precedes
     # the compressed encoding in each block, consisting of the bytes 0x43, 0x4B.
     # The maximum compressed size of each MSZIP block is 32k + 12 bytes."
-    assert compressed_size < chunk_size + 12
+    assert compressed_size <= chunk_size + 12
     output_file.write(struct.pack(CFDATA, 0, compressed_size, len(chunk)))
     output_file.write('\x43\x4b')  # MSZIP magic block header.
     output_file.write(compressed)