[wasm] Remove unused WasmException::empty_sig constant.

R=clemensh@chromium.org

Change-Id: If4086054af6125c252acfbf32074e40ed98b8222
Reviewed-on: https://chromium-review.googlesource.com/1206356
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55650}

src/wasm/wasm-module.cc

@@ -27,9 +27,6 @@ namespace v8 {
 namespace internal {
 namespace wasm {
 
-// static
-const WasmExceptionSig WasmException::empty_sig_(0, 0, nullptr);
-
 WireBytesRef WasmModule::LookupFunctionName(const ModuleWireBytes& wire_bytes,
                                             uint32_t function_index) const {
   if (!function_names) {

src/wasm/wasm-module.h

@@ -74,15 +74,12 @@ struct WasmGlobal {
 // function signature.
 typedef FunctionSig WasmExceptionSig;
 
+// Static representation of a wasm exception type.
 struct WasmException {
-  explicit WasmException(const WasmExceptionSig* sig = &empty_sig_)
-      : sig(sig) {}
+  explicit WasmException(const WasmExceptionSig* sig) : sig(sig) {}
   FunctionSig* ToFunctionSig() const { return const_cast<FunctionSig*>(sig); }
 
   const WasmExceptionSig* sig;  // type signature of the exception.
-
- private:
-  static const WasmExceptionSig empty_sig_;
 };
 
 // Static representation of a wasm data segment.