[SLC] extract non-common logic from computeModalityForMethod

^KTIJ-23783

analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/methods/SymbolLightSimpleMethod.kt

@@ -100,6 +100,10 @@ internal class SymbolLightSimpleMethod(
             result = modifiers
         )
 
+        if (functionSymbol.isExternal) {
+            modifiers.add(PsiModifier.NATIVE)
+        }
+
         modifiers.add(functionSymbol.toPsiVisibilityForMember())
 
         if (!suppressStatic && functionSymbol.hasJvmStaticAnnotation()) {

analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/symbolLightUtils.kt

@@ -89,10 +89,6 @@ internal fun KtSymbolWithModality.computeModalityForMethod(
         }
     }
 
-    if (this is KtFunctionSymbol && isExternal) {
-        result.add(PsiModifier.NATIVE)
-    }
-
     if (isTopLevel) {
         result.add(PsiModifier.STATIC)
         val needFinalModifier = when (this) {