Fir: simplify IrBuiltInsOverFir

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/SymbolTable.kt

@@ -459,6 +459,10 @@ open class SymbolTable(
         )
     }
 
+    fun declareClassWithSignature(sig: IdSignature, symbol: IrClassSymbol) {
+        classSymbolTable.set(sig, symbol)
+    }
+
     fun declareClassIfNotExists(descriptor: ClassDescriptor, classFactory: (IrClassSymbol) -> IrClass): IrClass =
         classSymbolTable.declareIfNotExists(descriptor, { signature -> createClassSymbol(descriptor, signature) }, classFactory)
 
@@ -846,6 +850,10 @@ open class SymbolTable(
         }
     }
 
+    fun declareSimpleFunctionWithSignature(sig: IdSignature, symbol: IrSimpleFunctionSymbol) {
+        simpleFunctionSymbolTable.set(sig, symbol)
+    }
+
     override fun referenceSimpleFunction(descriptor: FunctionDescriptor): IrSimpleFunctionSymbol =
         simpleFunctionSymbolTable.referenced(descriptor) { signature -> createSimpleFunctionSymbol(descriptor, signature) }