Reland "Keep a canonical list of shared function infos."

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 48043e62f815a351c1e189ca0b1e46d449a40703..0019b6d578c803af9f19376d253cfc8945165ef6 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5291,11 +5291,8 @@ void HOptimizedGraphBuilder::VisitFunctionLiteral(FunctionLiteral* expr) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
-  Handle<SharedFunctionInfo> shared_info = expr->shared_info();
-  if (shared_info.is_null()) {
-    shared_info =
-        Compiler::BuildFunctionInfo(expr, current_info()->script(), top_info());
-  }
+  Handle<SharedFunctionInfo> shared_info = Compiler::GetSharedFunctionInfo(
+      expr, current_info()->script(), top_info());
   // We also have a stack overflow if the recursive compilation did.
   if (HasStackOverflow()) return;
   HFunctionLiteral* instr =
@@ -11669,7 +11666,7 @@ void HOptimizedGraphBuilder::VisitFunctionDeclaration(
   switch (variable->location()) {
     case Variable::UNALLOCATED: {
       globals_.Add(variable->name(), zone());
-      Handle<SharedFunctionInfo> function = Compiler::BuildFunctionInfo(
+      Handle<SharedFunctionInfo> function = Compiler::GetSharedFunctionInfo(
           declaration->fun(), current_info()->script(), top_info());
       // Check for stack-overflow exception.
       if (function.is_null()) return SetStackOverflow();