Add Float objects to object links in Marshal.dump

spec/core/marshal/dump_spec.rb

@@ -313,9 +313,7 @@ def _dump(level)
     end
 
     it "uses object links for objects repeatedly dumped" do
-      NATFIXME 'it uses object links for objects repeatedly dumped', exception: SpecFailedException do
-        Marshal.dump([0.0, 0.0]).should == "\x04\b[\af\x060@\x06" # @\x06 is a link to the float value
-      end
+      Marshal.dump([0.0, 0.0]).should == "\x04\b[\af\x060@\x06" # @\x06 is a link to the float value
     end
   end
 
@@ -851,7 +849,7 @@ class << obj
 
     it "dumps a BasicObject subclass if it defines respond_to?" do
       obj = MarshalSpec::BasicObjectSubWithRespondToFalse.new
-      NATFIXME 'it dumps a BasicObject subclass if it defines respond_to?', exception: NoMethodError, message: /undefined method [`']nil\?' for an instance of MarshalSpec::BasicObjectSubWithRespondToFalse/ do
+      NATFIXME 'it dumps a BasicObject subclass if it defines respond_to?', exception: NoMethodError, message: /undefined method [`']is_a\?' for an instance of MarshalSpec::BasicObjectSubWithRespondToFalse/ do
         Marshal.dump(obj).should == "\x04\bo:2MarshalSpec::BasicObjectSubWithRespondToFalse\x00"
       end
     end

src/marshal.rb

@@ -336,10 +336,15 @@ def write(value)
       if value.respond_to?(:object_id) && @object_lookup.key?(value.object_id)
         write_object_link(@object_lookup.fetch(value.object_id))
         return @output
+      elsif value.is_a?(Float) && @object_lookup.key?(value)
+        write_object_link(@object_lookup.fetch(value))
+        return @output
       end
 
       if !value.nil? && !value.is_a?(TrueClass) && !value.is_a?(FalseClass) && !value.is_a?(Integer) && !value.is_a?(Float) && !value.is_a?(Symbol)
         @object_lookup[value.object_id] = @object_lookup.size
+      elsif value.is_a?(Float)
+        @object_lookup[value] = @object_lookup.size
       end
 
       ivars = value.instance_variables.map { |ivar_name| [ivar_name, value.instance_variable_get(ivar_name)] }