Generate TypedArrayInitialize builtin in hydrogen.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index b911c48252eb440da9979350f174be5e9c22125c..28cf4649307332dcfa22fae5e8bbee25611dba5b 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1562,6 +1562,21 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
       result = AssignEnvironment(result);
     }
     return result;
+  } else if (instr->representation().IsExternal()) {
+    ASSERT(instr->left()->representation().IsExternal());
+    ASSERT(instr->right()->representation().IsInteger32());
+    ASSERT(!instr->CheckFlag(HValue::kCanOverflow));
+    bool use_lea = LAddI::UseLea(instr);
+    LOperand* left = UseRegisterAtStart(instr->left());
+    HValue* right_candidate = instr->right();
+    LOperand* right = use_lea
+        ? UseRegisterOrConstantAtStart(right_candidate)
+        : UseOrConstantAtStart(right_candidate);
+    LAddI* add = new(zone()) LAddI(left, right);
+    LInstruction* result = use_lea
+        ? DefineAsRegister(add)
+        : DefineSameAsFirst(add);
+    return result;
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::ADD, instr);
   } else {