[es8] Initial set of changes to support syntactic tail calls.

test/mjsunit/es7/syntactic-tail-call-simple.js

Index: test/mjsunit/es7/syntactic-tail-call-simple.js
diff --git a/test/mjsunit/es6/tail-call-simple.js b/test/mjsunit/es7/syntactic-tail-call-simple.js
similarity index 70%
copy from test/mjsunit/es6/tail-call-simple.js
copy to test/mjsunit/es7/syntactic-tail-call-simple.js
index cc638082be592e953332cce27474daaecb68c2be..02f235e6d38230fe81ba9acd0b10e658de768846 100644
--- a/test/mjsunit/es6/tail-call-simple.js
+++ b/test/mjsunit/es7/syntactic-tail-call-simple.js
@@ -2,34 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony-tailcalls --stack-size=100
-
-//
-// Tail calls work only in strict mode.
-//
-(function() {
-  function f(n) {
-    if (n <= 0) {
-      return "foo";
-    }
-    return f(n - 1);
-  }
-  assertThrows(()=>{ f(1e5) });
-  %OptimizeFunctionOnNextCall(f);
-  assertThrows(()=>{ f(1e5) });
-})();
-
+// Flags: --allow-natives-syntax --harmony-explicit-tailcalls --stack-size=100
 
 //
 // Tail call normal functions.
 //
 (function() {
-  "use strict";
   function f(n) {
     if (n <= 0) {
       return "foo";
     }
-    return f(n - 1);
+    return continue f(n - 1);
   }
   assertEquals("foo", f(1e5));
   %OptimizeFunctionOnNextCall(f);
@@ -38,12 +21,11 @@
 
 
 (function() {
-  "use strict";
   function f(n) {
     if (n <= 0) {
       return  "foo";
     }
-    return f(n - 1, 42);  // Call with arguments adaptor.
+    return continue f(n - 1, 42);  // Call with arguments adaptor.
   }
   assertEquals("foo", f(1e5));
   %OptimizeFunctionOnNextCall(f);
@@ -52,18 +34,17 @@
 
 
 (function() {
-  "use strict";
   function f(n){
     if (n <= 0) {
       return "foo";
     }
-    return g(n - 1);
+    return continue g(n - 1);
   }
   function g(n){
     if (n <= 0) {
       return "bar";
     }
-    return f(n - 1);
+    return continue f(n - 1);
   }
   assertEquals("foo", f(1e5));
   assertEquals("bar", f(1e5 + 1));
@@ -74,18 +55,17 @@
 
 
 (function() {
-  "use strict";
   function f(n){
     if (n <= 0) {
       return "foo";
     }
-    return g(n - 1, 42);  // Call with arguments adaptor.
+    return continue g(n - 1, 42);  // Call with arguments adaptor.
   }
   function g(n){
     if (n <= 0) {
       return "bar";
     }
-    return f(n - 1, 42);  // Call with arguments adaptor.
+    return continue f(n - 1, 42);  // Call with arguments adaptor.
   }
   assertEquals("foo", f(1e5));
   assertEquals("bar", f(1e5 + 1));
@@ -99,16 +79,15 @@
 // Tail call bound functions.
 //
 (function() {
-  "use strict";
   function f0(n) {
     if (n <= 0) {
       return "foo";
     }
-    return f_bound(n - 1);
+    return continue f_bound(n - 1);
   }
   var f_bound = f0.bind({});
   function f(n) {
-    return f_bound(n);
+    return continue f_bound(n);
   }
   assertEquals("foo", f(1e5));
   %OptimizeFunctionOnNextCall(f);
@@ -117,23 +96,22 @@
 
 
 (function() {
-  "use strict";
   function f0(n){
     if (n <= 0) {
       return "foo";
     }
-    return g_bound(n - 1);
+    return continue g_bound(n - 1);
   }
   function g0(n){
     if (n <= 0) {
       return "bar";
     }
-    return f_bound(n - 1);
+    return continue f_bound(n - 1);
   }
   var f_bound = f0.bind({});
   var g_bound = g0.bind({});
   function f(n) {
-    return f_bound(n);
+    return continue f_bound(n);
   }
   assertEquals("foo", f(1e5));
   assertEquals("bar", f(1e5 + 1));