No use of WhenBuilder in introduceSubject

compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiFactory.kt

@@ -502,10 +502,6 @@ public class JetPsiFactory(private val project: Project) {
         }
     }
 
-    public fun WhenBuilder(): WhenBuilder {
-        return WhenBuilder(null: String?)
-    }
-
     public fun WhenBuilder(subject: JetExpression?): WhenBuilder {
         return WhenBuilder(subject?.getText())
     }

compiler/frontend/src/org/jetbrains/kotlin/psi/createByPattern.kt

@@ -198,7 +198,7 @@ public class ExpressionBuilder {
         return this
     }
 
-    public fun appendExpression(expression: JetExpression): ExpressionBuilder {
+    public fun appendExpression(expression: JetExpression?): ExpressionBuilder {
         patternBuilder.append("$" + arguments.size())
         arguments.add(expression)
         return this

compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/jetPsiUtil.kt

@@ -126,8 +126,8 @@ public fun <T: PsiElement> PsiElement.replaced(newElement: T): T = replace(newEl
 [suppress("UNCHECKED_CAST")]
 public fun <T: PsiElement> T.copied(): T = copy() as T
 
-public fun JetElement.blockExpressionsOrSingle(): Stream<JetElement> =
-        if (this is JetBlockExpression) getStatements().stream() else listOf(this).stream()
+public fun JetElement.blockExpressionsOrSingle(): Sequence<JetElement> =
+        if (this is JetBlockExpression) getStatements().asSequence() else sequenceOf(this)
 
 public fun JetElement.outermostLastBlockElement(predicate: (JetElement) -> Boolean = { true }): JetElement? {
     return JetPsiUtil.getOutermostLastBlockElement(this) { e -> e != null && predicate(e) }