Bug 1507520 - Make BigInt parsing dependent on run-time feature flag r=jandem,terpri

Differential Revision: https://phabricator.services.mozilla.com/D17349

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

js/public/CompileOptions.h

@@ -116,6 +116,7 @@ class JS_PUBLIC_API TransitiveCompileOptions {
   bool allowHTMLComments = true;
   bool isProbablySystemCode = false;
   bool hideScriptFromDebugger = false;
+  bool bigIntEnabledOption = false;
 
   /**
    * |introductionType| is a statically allocated C string: one of "eval",

js/src/frontend/TokenStream.cpp

@@ -2159,7 +2159,7 @@ MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::decimalNumber(
     }
   }
 #ifdef ENABLE_BIGINT
-  else if (unit == 'n') {
+  else if (unit == 'n' && anyCharsAccess().options().bigIntEnabledOption) {
     isBigInt = true;
     unit = peekCodeUnit();
   }
@@ -2365,6 +2365,7 @@ MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::regexpLiteral(
 template <typename Unit, class AnyCharsAccess>
 MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::bigIntLiteral(
     TokenStart start, Modifier modifier, TokenKind* out) {
+  MOZ_ASSERT(anyCharsAccess().options().bigIntEnabledOption);
   MOZ_ASSERT(this->sourceUnits.previousCodeUnit() == toUnit('n'));
   MOZ_ASSERT(this->sourceUnits.offset() > start.offset());
   uint32_t length = this->sourceUnits.offset() - start.offset();
@@ -2645,7 +2646,7 @@ MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::getTokenInternal(
       }
 
 #ifdef ENABLE_BIGINT
-      if (unit == 'n') {
+      if (unit == 'n' && anyCharsAccess().options().bigIntEnabledOption) {
         if (isLegacyOctalOrNoctal) {
           error(JSMSG_BIGINT_INVALID_SYNTAX);
           return badToken();

js/src/jsapi.cpp

@@ -3422,6 +3422,7 @@ void JS::TransitiveCompileOptions::copyPODTransitiveOptions(
   hasIntroductionInfo = rhs.hasIntroductionInfo;
   isProbablySystemCode = rhs.isProbablySystemCode;
   hideScriptFromDebugger = rhs.hideScriptFromDebugger;
+  bigIntEnabledOption = rhs.bigIntEnabledOption;
 };
 
 void JS::ReadOnlyCompileOptions::copyPODOptions(
@@ -3548,6 +3549,7 @@ JS::CompileOptions::CompileOptions(JSContext* cx)
   }
   throwOnAsmJSValidationFailureOption =
       cx->options().throwOnAsmJSValidationFailure();
+  bigIntEnabledOption = cx->realm()->creationOptions().getBigIntEnabled();
 }
 
 CompileOptions& CompileOptions::setIntroductionInfoToCaller(