dart2js cps: Hoist loop-invariant branches from loop entry.

pkg/compiler/lib/src/js_backend/codegen/task.dart

Index: pkg/compiler/lib/src/js_backend/codegen/task.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/task.dart b/pkg/compiler/lib/src/js_backend/codegen/task.dart
index cc78836a070652d371184f3f71dd9a6b3db267e7..034dd10ca8f3d3a0c16791144b881867b9ef0c21 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/task.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/task.dart
@@ -224,6 +224,7 @@ class CpsFunctionCompiler implements FunctionCompiler {
       applyCpsPass(new GVN(compiler, typeSystem), cpsFunction);
       applyCpsPass(new UpdateRefinements(typeSystem), cpsFunction);
       applyCpsPass(new BoundsChecker(typeSystem, compiler.world), cpsFunction);
+      applyCpsPass(new LoopInvariantBranchMotion(), cpsFunction);
       applyCpsPass(new ShrinkingReducer(), cpsFunction);
       applyCpsPass(new ScalarReplacer(compiler), cpsFunction);
       applyCpsPass(new MutableVariableEliminator(), cpsFunction);