[turbofan] Better typing of OSR context pointer

The Osr context is a pointer, and we can make it clear in the Typer.

Known pitfall: If we have a context within a context, the innner context
pointer is typed as Any.

Change-Id: Ia4d7e43ef42ef03f835e4b71d32d117ae835feee
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1741659Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63153}

src/compiler/typer.cc

@@ -787,7 +787,13 @@ Type Typer::Visitor::TypeParameter(Node* node) {
   return Type::NonInternal();
 }
 
-Type Typer::Visitor::TypeOsrValue(Node* node) { return Type::Any(); }
+Type Typer::Visitor::TypeOsrValue(Node* node) {
+  if (OsrValueIndexOf(node->op()) == Linkage::kOsrContextSpillSlotIndex) {
+    return Type::OtherInternal();
+  } else {
+    return Type::Any();
+  }
+}
 
 Type Typer::Visitor::TypeRetain(Node* node) { UNREACHABLE(); }