There are only 2 language modes, not 3

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 6d389d5b4e6e2618ed63ee0655237e1973f45f39..c367a79db5a6628558deef51af0c53f3b204a6aa 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -1845,8 +1845,8 @@ class StoreGlobalViaContextStub final : public PlatformCodeStub {
  private:
   class DepthBits : public BitField<int, 0, 4> {};
   STATIC_ASSERT(DepthBits::kMax == kMaximumDepth);
-  class LanguageModeBits : public BitField<LanguageMode, 4, 2> {};
-  STATIC_ASSERT(LANGUAGE_END == 3);
+  class LanguageModeBits : public BitField<LanguageMode, 4, 1> {};
+  STATIC_ASSERT(LANGUAGE_END == 2);
 
   DEFINE_CALL_INTERFACE_DESCRIPTOR(StoreGlobalViaContext);
   DEFINE_PLATFORM_CODE_STUB(StoreGlobalViaContext, PlatformCodeStub);