Get rid of HStringLength.

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 b5d01c8fa8defc08d1d4b9caad46e6b6957dafbd..31e54370e0a876d92ad4ae4e48e7358feb51a0eb 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -173,7 +173,6 @@ class LCodeGen;
   V(StringCharCodeAt)                           \
   V(StringCharFromCode)                         \
   V(StringCompareAndBranch)                     \
-  V(StringLength)                               \
   V(SubI)                                       \
   V(TaggedToI)                                  \
   V(ThisFunction)                               \
@@ -2224,19 +2223,6 @@ class LStringCharFromCode: public LTemplateInstruction<1, 1, 0> {
 };
 
 
-class LStringLength: public LTemplateInstruction<1, 1, 0> {
- public:
-  explicit LStringLength(LOperand* string) {
-    inputs_[0] = string;
-  }
-
-  LOperand* string() { return inputs_[0]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(StringLength, "string-length")
-  DECLARE_HYDROGEN_ACCESSOR(StringLength)
-};
-
-
 class LCheckFunction: public LTemplateInstruction<0, 1, 0> {
  public:
   explicit LCheckFunction(LOperand* value) {