Remove Johnson

No longer even compiles

Gemfile

@@ -3,7 +3,6 @@ source 'https://rubygems.org'
 gemspec
 
 group :test do
-  gem 'johnson'
   gem 'therubyracer', platform: :mri
   gem 'therubyrhino', ">=1.73.3", platform: :jruby
   gem 'minitest', require: false

lib/execjs/johnson_runtime.rb

@@ -1,104 +0,0 @@
-require "execjs/runtime"
-
-module ExecJS
-  class JohnsonRuntime < Runtime
-    class Context < Runtime::Context
-      def initialize(runtime, source = "")
-        source = encode(source)
-
-        @runtime = Johnson::Runtime.new
-        @runtime.evaluate(source)
-      end
-
-      def exec(source, options = {})
-        source = encode(source)
-
-        if /\S/ =~ source
-          eval "(function(){#{source}})()", options
-        end
-      end
-
-      def eval(source, options = {})
-        source = encode(source)
-
-        if /\S/ =~ source
-          unbox @runtime.evaluate("(#{source})")
-        end
-      rescue Johnson::Error => e
-        if syntax_error?(e)
-          raise RuntimeError, e.message
-        else
-          raise ProgramError, e.message
-        end
-      end
-
-      def call(properties, *args)
-        unbox @runtime.evaluate(properties).call(*args)
-      rescue Johnson::Error => e
-        if syntax_error?(e)
-          raise RuntimeError, e.message
-        else
-          raise ProgramError, e.message
-        end
-      end
-
-      def unbox(value)
-        case
-        when function?(value)
-          nil
-        when string?(value)
-          value.force_encoding('UTF-8')
-        when array?(value)
-          value.map { |v| unbox(v) }
-        when object?(value)
-          value.inject({}) do |vs, (k, v)|
-            vs[k] = unbox(v) unless function?(v)
-            vs
-          end
-        else
-          value
-        end
-      end
-
-      private
-        def syntax_error?(error)
-          error.message =~ /^syntax error at /
-        end
-
-        def function?(value)
-          value.respond_to?(:function?) && value.function?
-        end
-
-        def string?(value)
-          value.is_a?(String)
-        end
-
-        def array?(value)
-          array_test.call(value)
-        end
-
-        def object?(value)
-          value.respond_to?(:inject)
-        end
-
-        def array_test
-          @array_test ||= @runtime.evaluate("(function(a) {return a instanceof [].constructor})")
-        end
-    end
-
-    def name
-      "Johnson (SpiderMonkey)"
-    end
-
-    def available?
-      require "johnson"
-      true
-    rescue LoadError
-      false
-    end
-
-    def deprecated?
-      false
-    end
-  end
-end

lib/execjs/runtimes.rb

@@ -1,7 +1,6 @@
 require "execjs/module"
 require "execjs/disabled_runtime"
 require "execjs/external_runtime"
-require "execjs/johnson_runtime"
 require "execjs/ruby_racer_runtime"
 require "execjs/ruby_rhino_runtime"
 
@@ -13,8 +12,6 @@ module ExecJS
 
     RubyRhino = RubyRhinoRuntime.new
 
-    Johnson = JohnsonRuntime.new
-
     Node = ExternalRuntime.new(
       name:        "Node.js (V8)",
       command:     ["nodejs", "node"],
@@ -75,7 +72,6 @@ module ExecJS
       @runtimes ||= [
         RubyRacer,
         RubyRhino,
-        Johnson,
         JavaScriptCore,
         Node,
         SpiderMonkey,