Fix bug in LVA when running on closures directly.

* LVA usually runs on method scopes and in that context, runs on
  all scopes nested in it.

* But, 2689915 relaxed the constraint of running LVA on method
  scopes only as part of the series of commits to do more aggressive
  opts on blocks.

* This patch fixes a bug in LVA when LVA runs on a closure directly
  after its dynscope has been eliminated.

* We can now reorder DeadCodeElimination and OptimizeDynScopesPass
  in IRScope:optimizeSimpleScopes without crashing.

Author: subbuss

core/src/main/java/org/jruby/ir/passes/LiveVariableAnalysis.java

@@ -2,6 +2,7 @@
 
 import org.jruby.ir.IRClosure;
 import org.jruby.ir.IREvalScript;
+import org.jruby.ir.IRFlags;
 import org.jruby.ir.IRScope;
 import org.jruby.ir.instructions.ClosureAcceptingInstr;
 import org.jruby.ir.instructions.Instr;
@@ -81,7 +82,7 @@ public Object execute(IRScope scope, Object... data) {
             // conservatively assume that any dirtied variables that
             // belong to an outer scope are live on exit.
             Set<LocalVariable> nlVars = new HashSet<LocalVariable>();
-            collectNonLocalDirtyVars((IRClosure)scope, nlVars, 0);
+            collectNonLocalDirtyVars((IRClosure)scope, nlVars, scope.getFlags().contains(IRFlags.DYNSCOPE_ELIMINATED) ? -1 : 0);
 
             // Init DF vars from this set
             for (Variable v: nlVars) {