Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/src/compiler/representation-change.cc b/src/compiler/representation-change.cc
index 5dab60f..2f7720b 100644
--- a/src/compiler/representation-change.cc
+++ b/src/compiler/representation-change.cc
@@ -97,7 +97,6 @@
 
 namespace {
 
-// TODO(titzer): should Word64 also be implicitly convertable to others?
 bool IsWord(MachineRepresentation rep) {
   return rep == MachineRepresentation::kWord8 ||
          rep == MachineRepresentation::kWord16 ||
@@ -146,6 +145,9 @@
       return GetWord32RepresentationFor(node, output_rep, output_type);
     case MachineRepresentation::kWord64:
       return GetWord64RepresentationFor(node, output_rep, output_type);
+    case MachineRepresentation::kSimd128:  // Fall through.
+      // TODO(bbudge) Handle conversions between tagged and untagged.
+      break;
     case MachineRepresentation::kNone:
       return node;
   }