Bug 1599465 - Part 9: Add 'const' modifier to hash() and dump() methods. r=jwalden

An earlier part changed the `digit` function to be `const`, so we can now make
these two functions `const`, too.

Differential Revision: https://phabricator.services.mozilla.com/D54765

--HG--
extra : moz-landing-system : lando

js/src/vm/BigIntType.cpp

@@ -183,7 +183,7 @@ void BigInt::finalize(JSFreeOp* fop) {
   }
 }
 
-js::HashNumber BigInt::hash() {
+js::HashNumber BigInt::hash() const {
   js::HashNumber h =
       mozilla::HashBytes(digits().data(), digitLength() * sizeof(Digit));
   return mozilla::AddToHash(h, isNegative());
@@ -3511,12 +3511,12 @@ template JSAtom* js::BigIntToAtom<js::CanGC>(JSContext* cx, HandleBigInt bi);
 template JSAtom* js::BigIntToAtom<js::NoGC>(JSContext* cx, HandleBigInt bi);
 
 #if defined(DEBUG) || defined(JS_JITSPEW)
-void BigInt::dump() {
+void BigInt::dump() const {
   js::Fprinter out(stderr);
   dump(out);
 }
 
-void BigInt::dump(js::GenericPrinter& out) {
+void BigInt::dump(js::GenericPrinter& out) const {
   if (isNegative()) {
     out.putChar('-');
   }

js/src/vm/BigIntType.h

@@ -95,7 +95,7 @@ class BigInt final
 
   void traceChildren(JSTracer* trc);
   void finalize(JSFreeOp* fop);
-  js::HashNumber hash();
+  js::HashNumber hash() const;
   size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
 
   static BigInt* createUninitialized(JSContext* cx, size_t digitLength,
@@ -218,8 +218,8 @@ class BigInt final
                        mozilla::Maybe<bool>& res);
 
 #if defined(DEBUG) || defined(JS_JITSPEW)
-  void dump();  // Debugger-friendly stderr dump.
-  void dump(js::GenericPrinter& out);
+  void dump() const;  // Debugger-friendly stderr dump.
+  void dump(js::GenericPrinter& out) const;
 #endif
 
  private: