Fix Math.pow(-0, 0.5) and Math.pow(-0, -0.5). These are not equal to sqrt(-0...

src/assembler.cc

Index: src/assembler.cc
===================================================================
--- src/assembler.cc	(revision 6572)
+++ src/assembler.cc	(working copy)
@@ -838,8 +838,8 @@
     return power_double_int(x, y_int);  // Returns 1.0 for exponent 0.
   }
   if (!isinf(x)) {
-    if (y == 0.5) return sqrt(x);
-    if (y == -0.5) return 1.0 / sqrt(x);
+    if (y == 0.5) return sqrt(x + 0.0);  // -0 must be converted to +0.
+    if (y == -0.5) return 1.0 / sqrt(x + 0.0);
   }
   if (isnan(y) || ((x == 1 || x == -1) && isinf(y))) {
     return OS::nan_value();