[turbofan] Get rid of type lower bounds.

src/compiler/node.h

Index: src/compiler/node.h
diff --git a/src/compiler/node.h b/src/compiler/node.h
index e6c9f23fdc4daf1385bad1e11febe321e0fbacc8..bd129653bc3397510a53169c0ce48ae9ef411004 100644
--- a/src/compiler/node.h
+++ b/src/compiler/node.h
@@ -284,9 +284,9 @@ class Node final {
 
   void* operator new(size_t, void* location) { return location; }
 
-  // Only NodeProperties should manipulate the bounds.
-  Bounds bounds() const { return bounds_; }
-  void set_bounds(Bounds b) { bounds_ = b; }
+  // Only NodeProperties should manipulate the type.
+  Type* type() const { return type_; }
+  void set_type(Type* type) { type_ = type; }
 
   // Only NodeMarkers should manipulate the marks on nodes.
   Mark mark() { return mark_; }
@@ -306,7 +306,7 @@ class Node final {
   static const int kMaxInlineCapacity = InlineCapacityField::kMax - 1;
 
   const Operator* op_;
-  Bounds bounds_;
+  Type* type_;
   Mark mark_;
   uint32_t bit_field_;
   Use* first_use_;