Make x87 stack tracking more robust and avoid spilling

src/ia32/lithium-gap-resolver-ia32.cc

Index: src/ia32/lithium-gap-resolver-ia32.cc
diff --git a/src/ia32/lithium-gap-resolver-ia32.cc b/src/ia32/lithium-gap-resolver-ia32.cc
index b5bc18bdc9655987e4ba8e339883275d94fe80ad..eacd7337715a2c88e5adf8cc629b7323ddf3741b 100644
--- a/src/ia32/lithium-gap-resolver-ia32.cc
+++ b/src/ia32/lithium-gap-resolver-ia32.cc
@@ -365,10 +365,15 @@ void LGapResolver::EmitMove(int index) {
     } else {
       // load from the register onto the stack, store in destination, which must
       // be a double stack slot in the non-SSE2 case.
-      ASSERT(destination->IsDoubleStackSlot());
-      Operand dst = cgen_->ToOperand(destination);
       X87Register src = cgen_->ToX87Register(source);
-      cgen_->X87Mov(dst, src);
+      if (destination->IsDoubleStackSlot()) {
+        Operand dst = cgen_->ToOperand(destination);
+        cgen_->X87Mov(dst, src);
+      } else {
+        ASSERT(destination->IsDoubleRegister());
+        X87Register dst = cgen_->ToX87Register(destination);
+        cgen_->X87Mov(dst, src);
+      }
     }
   } else if (source->IsDoubleStackSlot()) {
     if (CpuFeatures::IsSupported(SSE2)) {