[wasm] [cleanup] Remove unused field

R=ahaas@chromium.org

Change-Id: I9b8a00061fe202b8c18426626b496c15455c8b7f
Reviewed-on: https://chromium-review.googlesource.com/660280Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47965}

test/cctest/wasm/wasm-run-utils.h

@@ -286,7 +286,6 @@ class WasmFunctionCompiler : public compiler::GraphAndBuilders {
   // The call descriptor is initialized when the function is compiled.
   CallDescriptor* descriptor_;
   TestingModuleBuilder* builder_;
-  Vector<const char> debug_name_;
   WasmFunction* function_;
   LocalDeclEncoder local_decls;
   compiler::SourcePositionTable source_position_table_;