Do not silently convert integers to doubles in binary operations. Only when at least one of argumen…

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 10316)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -1767,6 +1767,12 @@
                                         left,
                                         right);
 
+  // Binary operation of two Smi's produces a Smi not a double.
+  __ movq(temp, left);
+  __ orq(temp, right);
+  __ testq(temp, Immediate(kSmiTagMask));
+  __ j(ZERO, deopt);
+
   compiler->LoadDoubleOrSmiToXmm(XMM0, left, temp, deopt);
   compiler->LoadDoubleOrSmiToXmm(XMM1, right, temp, deopt);