[turbofan] Add re-typing for PlainPrimitiveToNumber during representation inference.

test/mjsunit/compiler/regress-628516.js

Index: test/mjsunit/compiler/regress-628516.js
diff --git a/test/mjsunit/ignition/dead-code-source-position.js b/test/mjsunit/compiler/regress-628516.js
similarity index 66%
copy from test/mjsunit/ignition/dead-code-source-position.js
copy to test/mjsunit/compiler/regress-628516.js
index 95bb9183b880229a703e58503e9aec2a673015aa..8cb43b4bea2cdbba9b4fe3400a70f66e02521e1f 100644
--- a/test/mjsunit/ignition/dead-code-source-position.js
+++ b/test/mjsunit/compiler/regress-628516.js
@@ -3,7 +3,11 @@
 // found in the LICENSE file.
 
 function f() {
-  for (f(x) in []) { f(new f()) }
+  var i = 0;
+  while (1) {
+    if ({}) i = expected[0] == x[0];
+    i++;
+  }
 }
 
-f();
+assertThrows(f);