[wasm][test] Remove unspec'ed name section code

This constant is unused, and should never be used, since name sections
are encoded as an unknown section with the special name "name".

R=ahaas@chromium.org

Change-Id: I2fa1a21506dbe30033aecb3c1bf9ad84b6b872bc
Reviewed-on: https://chromium-review.googlesource.com/c/1352305Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57905}

test/mjsunit/wasm/wasm-constants.js

@@ -64,7 +64,6 @@ let kStartSectionCode = 8;       // Start function declaration
 let kElementSectionCode = 9;     // Elements section
 let kCodeSectionCode = 10;       // Function code
 let kDataSectionCode = 11;       // Data segments
-let kNameSectionCode = 12;       // Name section (encoded as string)
 let kExceptionSectionCode = 13;  // Exception section (must appear before code section)
 
 // Name section types