[turbofan] Try hard(er) to use smi representation for float64 values.

test/mjsunit/regress/regress-95113.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (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
 
 function get_double_array() {
   var a = new Array(100000);
   var i = 0;
   while (!%HasFastDoubleElements(a)) {
-    a[i] = i;
-    i += 0.5;
+    a[i] = i + 0.1;
+    i += 1;
   }
   assertTrue(%HasFastDoubleElements(a));
   a.length = 1;
   a[0] = 1.5;
   a.length = 2;
   a[1] = 2.5;
   assertEquals(a[0], 1.5);
   assertEquals(a[1], 2.5);
   assertTrue(%HasFastDoubleElements(a));
   return a;
 }
 
 var a = get_double_array();