[turbofan] Transfer types from loop phis to OSR values.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index e9f3a3564ffd8da3e93b35b4eb8c644fb7baad32..24d02446e1131a869282b098f6cde6c71a6ac75e 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -596,11 +596,16 @@ Bounds Typer::Visitor::TypeParameter(Node* node) {
 
 
 Bounds Typer::Visitor::TypeOsrValue(Node* node) {
-  // OSR values explicitly have type {None} before OSR form is deconstructed.
   if (node->InputAt(0)->opcode() == IrOpcode::kOsrLoopEntry) {
+    // Before deconstruction, OSR values have type {None} to avoid polluting
+    // the types of phis and other nodes in the graph.
     return Bounds(Type::None(), Type::None());
   }
-  // TODO(turbofan): preserve the type of OSR values after deconstruction.
+  if (NodeProperties::IsTyped(node)) {
+    // After deconstruction, OSR values may have had a type explicitly set.
+    return NodeProperties::GetBounds(node);
+  }
+  // Otherwise, be conservative.
   return Bounds::Unbounded(zone());
 }