[turbofan] Initial support for escape analysis.

test/mjsunit/compiler/escape-analysis-6.js

Index: test/mjsunit/compiler/escape-analysis-6.js
diff --git a/test/mjsunit/d8-worker-spawn-worker.js b/test/mjsunit/compiler/escape-analysis-6.js
similarity index 82%
copy from test/mjsunit/d8-worker-spawn-worker.js
copy to test/mjsunit/compiler/escape-analysis-6.js
index a114d8587e0ebc7095565cfebb3634e7fdefbbe7..6143cfbc1f61adcbff418900cfdd1df52336435e 100644
--- a/test/mjsunit/d8-worker-spawn-worker.js
+++ b/test/mjsunit/compiler/escape-analysis-6.js
@@ -25,16 +25,24 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-if (this.Worker) {
-  var workerScript =
-    `var w = new Worker('postMessage(42)');
-     onmessage = function(parentMsg) {
-       w.postMessage(parentMsg);
-       var childMsg = w.getMessage();
-       postMessage(childMsg);
-     };`;
+// Flags: --allow-natives-syntax --turbo-escape
+//
+
+function f(a) {
+  "use strict";
+  return arguments;
+}
 
-  var w = new Worker(workerScript);
-  w.postMessage(9);
-  assertEquals(42, w.getMessage());
+function g() {
+  "use strict";
+  var x = f(1,2,3);
+  while (x.length < 4) {
+      x = f(4,5,6,7,8);
+  }
+  return x.length;
 }
+
+assertEquals(5, g());
+assertEquals(5, g());
+%OptimizeFunctionOnNextCall(g);
+assertEquals(5, g());