[crankshaft] Fix deopt loop in String.fromCharCode on non-int32 inputs.

test/mjsunit/regress/regress-crbug-587068.js

Index: test/mjsunit/regress/regress-crbug-587068.js
diff --git a/test/mjsunit/regress/regress-3650-3.js b/test/mjsunit/regress/regress-crbug-587068.js
similarity index 57%
copy from test/mjsunit/regress/regress-3650-3.js
copy to test/mjsunit/regress/regress-crbug-587068.js
index 013e4df2834e20435982300303eb6260eb41b2be..4cdd3ffbdb88ada04ae4c3f47874f0afdc8ad86c 100644
--- a/test/mjsunit/regress/regress-3650-3.js
+++ b/test/mjsunit/regress/regress-crbug-587068.js
@@ -4,14 +4,11 @@
 
 // Flags: --allow-natives-syntax
 
-function foo(a) {
-  for (var d in a) {
-    delete a[1];
-  }
-}
-
-foo([1,2,3]);
-foo([2,3,4]);
+// The Crankshaft fast case for String.fromCharCode used to unconditionally
+// deoptimize on non int32 indices.
+function foo(i) { return String.fromCharCode(i); }
+foo(33);
+foo(33);
 %OptimizeFunctionOnNextCall(foo);
-foo([1,2,3]);
+foo(33.3);
 assertOptimized(foo);