Introduce runtime function %OptimizeFunctionOnNextCall to manually trigger optimization.

test/mjsunit/regress/regress-3218915.js

Index: test/mjsunit/regress/regress-3218915.js
diff --git a/test/mjsunit/regress/regress-3218915.js b/test/mjsunit/regress/regress-3218915.js
index 5fcbcec31d59140697f8c900ca02652fa5c19b72..4b08a6e82508309459ff5dc18d4994fad76effe3 100644
--- a/test/mjsunit/regress/regress-3218915.js
+++ b/test/mjsunit/regress/regress-3218915.js
@@ -25,6 +25,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Flags: --allow-natives-syntax
+
 // Checks that comma expression in conditional context is processed correctly.
 
 function withCommaExpressionInConditional(x) {
@@ -36,7 +38,9 @@ function withCommaExpressionInConditional(x) {
   return (y = x + 1, y > 1) ? 'medium' : 'small';
 }
 
-for (var i = 0; i < 10000; i++) {
+for (var i = 0; i < 5; i++) {
   withCommaExpressionInConditional(i);
 }
+%OptimizeFunctionOnNextCall(withCommaExpressionInConditional);
+withCommaExpressionInConditional(i);
 withCommaExpressionInConditional("1")