[JS IR] Treat char as inline class no matter how it's declared

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/JsInlineClassesUtils.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.ir.backend.js.JsCommonInlineClassesUtils
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
+import org.jetbrains.kotlin.ir.types.IdSignatureValues
 import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.isMarkedNullable
@@ -38,8 +39,11 @@ class JsInlineClassesUtils(val context: JsIrBackendContext) : JsCommonInlineClas
         return null
     }
 
+    // Char is declared as a regular class, but we want to treat it as an inline class.
+    // We can't declare it as an inline/value class for compatibility reasons.
+    // For example, applying the === operator will stop working if Char becomes an inline class.
     override fun isClassInlineLike(klass: IrClass): Boolean =
-        klass.isInline
+        super.isClassInlineLike(klass) || klass.symbol.signature == IdSignatureValues._char
 
     override val boxIntrinsic: IrSimpleFunctionSymbol
         get() = context.intrinsics.jsBoxIntrinsic