Minor in JS backend: add @Nullable to JsNameRef#getQualifier and JsNameRef#getSymbol.

js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/JsNameRef.java

@@ -50,11 +50,13 @@ public final class JsNameRef extends JsExpressionImpl implements HasName {
         return name;
     }
 
+    @Nullable
     @Override
     public Symbol getSymbol() {
         return name;
     }
 
+    @Nullable
     public JsExpression getQualifier() {
         return qualifier;
     }

js/js.inliner/src/org/jetbrains/kotlin/js/inline/context/FunctionContext.kt

@@ -70,7 +70,7 @@ abstract class FunctionContext(
             val staticRef = callName.staticRef
             if (staticRef !is JsFunction) continue
 
-            val functionCalled = staticRef as JsFunction
+            val functionCalled = staticRef
             if (isFunctionCreator(functionCalled)) {
                 declareFunctionConstructorCall(call)
             }
@@ -120,7 +120,7 @@ abstract class FunctionContext(
 
         /** remove ending `.call()` */
         if (isCallInvocation(call)) {
-            callQualifier = (callQualifier as JsNameRef).getQualifier()
+            callQualifier = (callQualifier as JsNameRef).getQualifier()!!
         }
 
         /** in case 4, 5 get ref (reduce 4, 5 to 2, 3 accordingly) */

js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/invocationUtils.kt

@@ -42,7 +42,7 @@ public fun getSimpleName(call: JsInvocation): JsName? {
  * @returns first name ident (iterating through qualifier chain)
  */
 public fun getSimpleIdent(call: JsInvocation): String? {
-    var qualifier = call.getQualifier()
+    var qualifier: JsExpression? = call.getQualifier()
     
     while (qualifier != null) {
         when (qualifier) {