Restore saved caller FP registers on stub failure

src/arguments.h

Index: src/arguments.h
diff --git a/src/arguments.h b/src/arguments.h
index 92e57401f2c27ad710b6e235eaabe0f8b7f1de8f..c1eabfd310f2bfd8730d74f537220a7188fd29d8 100644
--- a/src/arguments.h
+++ b/src/arguments.h
@@ -289,12 +289,21 @@ class FunctionCallbackArguments
 };
 
 
+#ifdef DEBUG
+double ClobberDoubleRegisters(double x1, double x2, double x3, double x4);
+#define CLOBBER_DOUBLE_REGISTERS() ClobberDoubleRegisters(1, 2, 3, 4);
+#else
+#define CLOBBER_DOUBLE_REGISTERS()
+#endif
+
+
 #define DECLARE_RUNTIME_FUNCTION(Type, Name)    \
 Type Name(int args_length, Object** args_object, Isolate* isolate)
 
 #define RUNTIME_FUNCTION(Type, Name)                                  \
 static Type __RT_impl_##Name(Arguments args, Isolate* isolate);       \
 Type Name(int args_length, Object** args_object, Isolate* isolate) {  \
+  CLOBBER_DOUBLE_REGISTERS();                                         \
   Arguments args(args_length, args_object);                           \
   return __RT_impl_##Name(args, isolate);                             \
 }                                                                     \