DevTools: Convert inspector-unit tests to use reusable test harness

third_party/WebKit/LayoutTests/http/tests/inspector-unit/text-prompt.js

+TestRunner.addResult("This tests if the TextPrompt autocomplete works properly.");
+
+var suggestions = ["heyoo", "hey it's a suggestion", "hey another suggestion"].map(s => ({title: s}));
+var prompt = new UI.TextPrompt();
+prompt.initialize(() => Promise.resolve(suggestions));
+var div = document.createElement("div");
+UI.inspectorView.element.appendChild(div);
+prompt.attachAndStartEditing(div);
+prompt.setText("hey");
+TestRunner.addSniffer(prompt, "_completionsReady").then(step2);
+prompt.complete();
+function step2() {
+    TestRunner.addResult("Text:" + prompt.text());
+    TestRunner.addResult("TextWithCurrentSuggestion:" + prompt.textWithCurrentSuggestion());
+
+    TestRunner.addResult("Test with inexact match:");
+    prompt.clearAutocomplete();
+    prompt.setText("inexactmatch");
+    TestRunner.addSniffer(prompt, "_completionsReady").then(step3);
+    prompt.complete();
+}
+function step3() {
+    TestRunner.addResult("Text:" + prompt.text());
+    TestRunner.addResult("TextWithCurrentSuggestion:" + prompt.textWithCurrentSuggestion());
+    TestRunner.completeTest();
+}