file_reference: Remove all build files when file reference is removed.

A build file doesn't have any meaning without its underyling file
reference, as it can't be built.
In this commit, when a file reference is removed, in addition to the
previouls file reference removal logic, the build files that refer to
the file references are removed as well.

lib/xcodeproj/project/object/file_reference.rb

@@ -313,8 +313,7 @@ def target_dependency_proxies
         end
 
         # In addition to removing the file reference, this will also remove any
-        # items related to this reference in case it represents an external
-        # Xcode project.
+        # items related to this reference.
         #
         # @see AbstractObject#remove_from_project
         #
@@ -327,6 +326,8 @@ def remove_from_project
             project_reference[:product_group].remove_from_project
             project.root_object.project_references.delete(project_reference)
           end
+
+          build_files.each(&:remove_from_project)
           super
         end
 

spec/project/object/file_reference_spec.rb

@@ -75,6 +75,14 @@ module ProjectSpecs
       @file.comments.should == 'This file was automatically generated.'
     end
 
+    it 'removes the build files when removing the file reference' do
+      @target = @project.new_target(:static_library, 'Pods', :ios)
+      @target.build_phases[0].add_file_reference(@file)
+
+      @file.remove_from_project
+      @target.build_phases[0].files.should.be.empty
+    end
+
     describe 'concerning proxies' do
       it 'returns that it is not a proxy' do
         @file.should.not.be.a.proxy