ARM: Make use of d16-d31 when available.

src/frames.cc

Index: src/frames.cc
diff --git a/src/frames.cc b/src/frames.cc
index 23bcedae1f9fc32d77c45fb15b46df30c7a2222c..7f0a48dc6c44f020d14252c3d503eabcc11585f2 100644
--- a/src/frames.cc
+++ b/src/frames.cc
@@ -643,6 +643,8 @@ void StandardFrame::IterateCompiledFrame(ObjectVisitor* v) const {
 
   // Skip saved double registers.
   if (safepoint_entry.has_doubles()) {
+    // Number of doubles not known at snapshot time.
+    ASSERT(!Serializer::enabled());
     parameters_base += DoubleRegister::NumAllocatableRegisters() *
         kDoubleSize / kPointerSize;
   }