[turbofan] Print API for Node.

Node has an operator<<, however, constructing an ostream in a debugger
session is non-trivial, hence this method.

BUG=

Review URL: https://codereview.chromium.org/1488953003

Cr-Commit-Position: refs/heads/master@{#32439}

src/compiler/node.cc

@@ -271,6 +271,12 @@ bool Node::OwnedBy(Node const* owner1, Node const* owner2) const {
 }
 
 
+void Node::Print() const {
+  OFStream os(stdout);
+  os << *this << std::endl;
+}
+
+
 Node::Node(NodeId id, const Operator* op, int inline_count, int inline_capacity)
     : op_(op),
       type_(nullptr),

src/compiler/node.h

@@ -186,6 +186,7 @@ class Node final {
 
   // Returns true if {owner1} and {owner2} are the only users of {this} node.
   bool OwnedBy(Node const* owner1, Node const* owner2) const;
+  void Print() const;
 
  private:
   struct Use;