Adds a flag to the standalone vm to throw an exception on 53-bit integer overflow.

runtime/lib/double.cc

Index: runtime/lib/double.cc
===================================================================
--- runtime/lib/double.cc	(revision 23032)
+++ runtime/lib/double.cc	(working copy)
@@ -16,6 +16,7 @@
 
 namespace dart {
 
+DECLARE_FLAG(bool, throw_on_javascript_int_overflow);
 DECLARE_FLAG(bool, trace_intrinsified_natives);
 
 DEFINE_NATIVE_ENTRY(Double_doubleFromInteger, 2) {
@@ -81,7 +82,12 @@
   }
   const Bigint& big = Bigint::Handle(BigintOperations::NewFromDouble(val));
   if (BigintOperations::FitsIntoInt64(big)) {
-    return Integer::New(BigintOperations::ToInt64(big));
+    const Integer& i = Integer::Handle(
+        Integer::New(BigintOperations::ToInt64(big)));
+    if (FLAG_throw_on_javascript_int_overflow && !i.FitsIn53Bits()) {

[siva, 2013/05/23 17:38:57]

just
if (FLAG_throw_on_javascript_int_overflow) {
 ....
}

The FitsIn53Bits check is already inside CheckForFifty...

+      Integer::CheckForFiftyThreeBitOverflow(i, "DoubleToInteger");
+    }
+    return i.raw();
   } else {
     return big.raw();
   }