Add support for IncrementCounter in Hydrogen.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 32ee0b9d31daf38d44bcd9683cfeb8d2b22297e8..9addcf345a27cbb26c0a4c072bcf190905b95b4a 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -85,6 +85,7 @@ class LCodeGen;
   V(CmpMapAndBranch)                            \
   V(CmpT)                                       \
   V(ConstantD)                                  \
+  V(ConstantE)                                  \
   V(ConstantI)                                  \
   V(ConstantS)                                  \
   V(ConstantT)                                  \
@@ -1186,6 +1187,15 @@ class LConstantD: public LTemplateInstruction<1, 0, 1> {
 };
 
 
+class LConstantE: public LTemplateInstruction<1, 0, 0> {
+ public:
+  DECLARE_CONCRETE_INSTRUCTION(ConstantE, "constant-e")
+  DECLARE_HYDROGEN_ACCESSOR(Constant)
+
+  ExternalReference value() const { return hydrogen()->ExternalValue(); }
+};
+
+
 class LConstantT: public LTemplateInstruction<1, 0, 0> {
  public:
   DECLARE_CONCRETE_INSTRUCTION(ConstantT, "constant-t")