Revert "It appears getLexicalScopes can return null now."

This reverts commit ca14416.

Author: headius

core/src/main/java/org/jruby/ir/persistence/IRWriter.java

@@ -34,10 +34,8 @@ public static void persist(IRWriterEncoder file, IRScope script) throws IOExcept
     private static void persistScopeInstructions(IRWriterEncoder file, IRScope parent) {
         persistScopeInstrs(file, parent);
 
-        if (parent.getLexicalScopes() != null) {
-            for (IRScope scope: parent.getLexicalScopes()) {
-                persistScopeInstructions(file, scope);
-            }
+        for (IRScope scope: parent.getLexicalScopes()) {
+            persistScopeInstructions(file, scope);
         }
     }
 
@@ -62,10 +60,8 @@ private static void persistScopeInstrs(IRWriterEncoder file, IRScope scope) {
     private static void persistScopeHeaders(IRWriterEncoder file, IRScope parent) {
         persistScopeHeader(file, parent);
 
-        if (parent.getLexicalScopes() != null) {
-            for (IRScope scope : parent.getLexicalScopes()) {
-                persistScopeHeaders(file, scope);
-            }
+        for (IRScope scope: parent.getLexicalScopes()) {
+            persistScopeHeaders(file, scope);
         }
     }