Fix plugin test that replaces parser

This test broke down aftert I intergrated the AST utils directly into the Grammar class, then I had problems importing the PEG.js parser to use the Grammar class, but found a workaround using 'process.cwd()'

test/spec/api/plugin-api.spec.js

@@ -102,19 +102,20 @@ describe( "plugin API", function () {
 
                     config.parser = peg.generate( `
 
+                        {
+                            const pp = require( process.cwd() + "/lib/peg" ).parser;
+                        }
+
                         start = .* {
-                            return {
+                            return new pp.Grammar( void 0, [{
-                                type: 'grammar',
+                                type: "rule",
-                                rules: [{
+                                name: "start",
-                                    type: 'rule',
+                                expression: {
-                                    name: 'start',
+                                    type: "literal",
-                                    expression: {
+                                    value: text(),
-                                        type: 'literal',
+                                    ignoreCase: false
-                                        value: text(),
+                                }
-                                        ignoreCase: false
+                            }] );
-                                    }
-                                }]
-                            };
                         }
 
                     ` );