There are only 2 language modes, not 3

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 1b0ded0aa82eaf2254a3742bc2d07aacefaf9f38..58b110f07800ce07418324e0e4386f61c499610a 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4401,9 +4401,9 @@ class ScopeInfo : public FixedArray {
   // Properties of scopes.
   class ScopeTypeField : public BitField<ScopeType, 0, 4> {};
   class CallsEvalField : public BitField<bool, ScopeTypeField::kNext, 1> {};
-  STATIC_ASSERT(LANGUAGE_END == 3);
+  STATIC_ASSERT(LANGUAGE_END == 2);
   class LanguageModeField
-      : public BitField<LanguageMode, CallsEvalField::kNext, 2> {};
+      : public BitField<LanguageMode, CallsEvalField::kNext, 1> {};
   class DeclarationScopeField
       : public BitField<bool, LanguageModeField::kNext, 1> {};
   class ReceiverVariableField
@@ -7581,8 +7581,6 @@ class SharedFunctionInfo: public HeapObject {
     kIsDeclaration,
     kCompilerHintsCount,  // Pseudo entry
   };
-  // Add hints for other modes when they're added.
-  STATIC_ASSERT(LANGUAGE_END == 3);
   // kFunctionKind has to be byte-aligned
   STATIC_ASSERT((kFunctionKind % kBitsPerByte) == 0);
 // Make sure that FunctionKind and byte 2 are in sync: