Restore LocalOptimizationPass

* While this doesn't do a while lot right now, it does opt
  some scenarios (some forms of multiple-assignment).
* During refactorings and cleanup work between pre1 and pre2,
  we lost the code that actually ran it. Restoring it here.

Author: subbuss

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

@@ -7,6 +7,7 @@
 import org.jruby.ir.instructions.ResultInstr;
 import org.jruby.ir.operands.Operand;
 import org.jruby.ir.operands.Variable;
+import org.jruby.ir.representations.BasicBlock;
 
 import java.util.*;
 
@@ -18,6 +19,10 @@ public String getLabel() {
 
     @Override
     public Object execute(IRScope s, Object... data) {
+        for (BasicBlock b: s.getCFG().getBasicBlocks()) {
+            runLocalOptsOnInstrList(s, b.getInstrs().listIterator(), false);
+        }
+
         // SSS FIXME: What is this about? 
         // Why 'Only after running local opts'? Figure out and document.
         //