[intrinsics] Drop the now obsolete %_DoubleHi and %_DoubleLo intrinsics.

src/crankshaft/mips/lithium-mips.cc

Index: src/crankshaft/mips/lithium-mips.cc
diff --git a/src/crankshaft/mips/lithium-mips.cc b/src/crankshaft/mips/lithium-mips.cc
index e7066209c4de6289c02adc083b2ce03e1c926f70..dc8a99f28fd5b236f2e874b1ebec58535f8792a0 100644
--- a/src/crankshaft/mips/lithium-mips.cc
+++ b/src/crankshaft/mips/lithium-mips.cc
@@ -1927,13 +1927,6 @@ LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
 }
 
 
-LInstruction* LChunkBuilder::DoDoubleBits(HDoubleBits* instr) {
-  HValue* value = instr->value();
-  DCHECK(value->representation().IsDouble());
-  return DefineAsRegister(new(zone()) LDoubleBits(UseRegister(value)));
-}
-
-
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   LOperand* context = info()->IsStub()
       ? UseFixed(instr->context(), cp)