[wasm] Remove unnecessary default parameter

R=clemensb@chromium.org

Bug: v8:12926
Change-Id: I426f06ca159c109109b0390494d8f1b5e274c888
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4004400
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84061}

src/wasm/module-decoder-impl.h

@@ -1635,7 +1635,7 @@ class ModuleDecoderTemplate : public Decoder {
 
   // Decodes an entire module.
   ModuleResult DecodeModule(Counters* counters, AccountingAllocator* allocator,
-                            bool validate_functions = true) {
+                            bool validate_functions) {
     StartDecoding(counters, allocator);
     uint32_t offset = 0;
     base::Vector<const byte> orig_bytes(start(), end() - start());