Migrated several tests from blink to V8 repository.

test/webkit/dfg-cfg-simplify-eliminate-set-local-type-check-then-branch-not-null-and-decrement.js

Index: test/webkit/dfg-cfg-simplify-eliminate-set-local-type-check-then-branch-not-null-and-decrement.js
diff --git a/test/webkit/concat-while-having-a-bad-time.js b/test/webkit/dfg-cfg-simplify-eliminate-set-local-type-check-then-branch-not-null-and-decrement.js
similarity index 69%
copy from test/webkit/concat-while-having-a-bad-time.js
copy to test/webkit/dfg-cfg-simplify-eliminate-set-local-type-check-then-branch-not-null-and-decrement.js
index dfda1e08a0b36194b787a44ee12a9693acd8aeaf..cac2d102415b699bfdcffdfd3b43ffaa5183950d 100644
--- a/test/webkit/concat-while-having-a-bad-time.js
+++ b/test/webkit/dfg-cfg-simplify-eliminate-set-local-type-check-then-branch-not-null-and-decrement.js
@@ -22,10 +22,34 @@
 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 description(
-"Tests the behavior of Array.prototype.concat while the array is having a bad time due to one of the elements we are concatenating."
+"Tests what happens when CFG simplification leads to the elimination of a set local that had a type check, and then we branch on the variable not being null while decrementing the variable in the same basic block."
 );
 
-Object.defineProperty(Array.prototype, 0, { writable: false });
-shouldBe("[42].concat()", "[42]");
+function foo(o) {
+    var x;
+    if (o.f)
+        x = o.g;
+    else
+        x = o.h;
+    var y = x != null;
+    x--;
+    if (y)
+        return y;
+    else
+        return false;
+}
+
+for (var i = 0; i < 500; ++i) {
+    var o = {f:foo};
+    var expected;
+    if (i < 450) {
+        o.g = i;
+        expected = "true";
+    } else {
+        o.g = null;
+        expected = "false";
+    }
+    shouldBe("foo(o)", expected);
+}