Add support for IncrementCounter in Hydrogen.

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index fd3fd3ad4c20f5848ca1ffdf2a25f5002b8ecb57..5cfca0001004e7140e4fd47dbdd8fc7732053deb 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -2017,6 +2017,8 @@ LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
     return DefineAsRegister(new(zone()) LConstantI);
   } else if (r.IsDouble()) {
     return DefineAsRegister(new(zone()) LConstantD);
+  } else if (r.IsExternal()) {
+    return DefineAsRegister(new(zone()) LConstantE);
   } else if (r.IsTagged()) {
     return DefineAsRegister(new(zone()) LConstantT);
   } else {