diff --git a/browser/base/content/test/general/domplate_test.js b/browser/base/content/test/general/domplate_test.js
index 75f2b25e2a5..b340b22ed61 100644
--- a/browser/base/content/test/general/domplate_test.js
+++ b/browser/base/content/test/general/domplate_test.js
@@ -46,6 +46,6 @@ function test()
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic domplate tests";
+  content.location = "data:text/html;charset=utf-8,domplate_test.js";
 }
 
diff --git a/browser/devtools/inspector/test/browser_inspector_basic_highlighter.js b/browser/devtools/inspector/test/browser_inspector_basic_highlighter.js
index bc3eabddbd0..01b7f6dd303 100644
--- a/browser/devtools/inspector/test/browser_inspector_basic_highlighter.js
+++ b/browser/devtools/inspector/test/browser_inspector_basic_highlighter.js
@@ -18,7 +18,7 @@ function test() {
     waitForFocus(setupTest, content);
   }, true);
 
-  content.location = "data:text/html,<h1>foo</h1><h2>bar</h2>";
+  content.location = "data:text/html;charset=utf-8,<h1>foo</h1><span>bar</span>";
 
   function setupTest() {
     openInspector((aInspector, aToolbox) => {
@@ -29,8 +29,7 @@ function test() {
     });
   }
 
-  function runTests(aInspector) {
-    getHighlighterOutline().setAttribute("disable-transitions", "true");
+  function runTests() {
     Task.spawn(function() {
       yield hoverH1InMarkupView();
       yield assertH1Highlighted();
diff --git a/browser/devtools/inspector/test/browser_inspector_bug_650804_search.js b/browser/devtools/inspector/test/browser_inspector_bug_650804_search.js
index ad889ba7285..3cb83918a8f 100644
--- a/browser/devtools/inspector/test/browser_inspector_bug_650804_search.js
+++ b/browser/devtools/inspector/test/browser_inspector_bug_650804_search.js
@@ -52,7 +52,8 @@ function test()
     waitForFocus(setupTest, content);
   }, true);
 
-  content.location = "http://mochi.test:8888/browser/browser/devtools/inspector/test/browser_inspector_bug_650804_search.html";
+  content.location = "http://mochi.test:8888/browser/browser/devtools/" +
+                     "inspector/test/browser_inspector_bug_650804_search.html";
 
   function $(id) {
     if (id == null) return null;
diff --git a/browser/devtools/inspector/test/browser_inspector_bug_674871.js b/browser/devtools/inspector/test/browser_inspector_bug_674871.js
index 7d2e508e807..ebd31c4b772 100644
--- a/browser/devtools/inspector/test/browser_inspector_bug_674871.js
+++ b/browser/devtools/inspector/test/browser_inspector_bug_674871.js
@@ -50,7 +50,6 @@ function test()
       inspector = aInspector;
       // Make sure the highlighter is shown so we can disable transitions
       inspector.toolbox.highlighter.showBoxModel(getNodeFront(doc.body)).then(() => {
-        getHighlighterOutline().setAttribute("disable-transitions", "true");
         runTests();
       });
     });
diff --git a/browser/devtools/inspector/test/browser_inspector_bug_699308_iframe_navigation.js b/browser/devtools/inspector/test/browser_inspector_bug_699308_iframe_navigation.js
index ee6689727ed..c253e9629d3 100644
--- a/browser/devtools/inspector/test/browser_inspector_bug_699308_iframe_navigation.js
+++ b/browser/devtools/inspector/test/browser_inspector_bug_699308_iframe_navigation.js
@@ -78,6 +78,7 @@ function test() {
     waitForFocus(startTest, content);
   }, true);
 
-  content.location = "data:text/html,<p>bug 699308 - test iframe navigation" +
-    "<iframe src='data:text/html,hello world'></iframe>";
+  content.location = "data:text/html;charset=utf-8," +
+                     "<p>bug 699308 - test iframe navigation</p>" +
+                     "<iframe src='data:text/html;charset=utf-8,hello world'></iframe>";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_bug_958456_highlight_comments.js b/browser/devtools/inspector/test/browser_inspector_bug_958456_highlight_comments.js
index 57b1fab1443..756ce0ee58e 100644
--- a/browser/devtools/inspector/test/browser_inspector_bug_958456_highlight_comments.js
+++ b/browser/devtools/inspector/test/browser_inspector_bug_958456_highlight_comments.js
@@ -77,7 +77,6 @@ function prepareHighlighter() {
   let deferred = promise.defer();
   inspector.selection.setNode(doc.querySelector("p"), null);
   inspector.once("inspector-updated", () => {
-    getHighlighterOutline().setAttribute("disable-transitions", "true");
     deferred.resolve();
   });
   return deferred.promise;
diff --git a/browser/devtools/inspector/test/browser_inspector_changes.js b/browser/devtools/inspector/test/browser_inspector_changes.js
index e391adcc668..fc76792af6b 100644
--- a/browser/devtools/inspector/test/browser_inspector_changes.js
+++ b/browser/devtools/inspector/test/browser_inspector_changes.js
@@ -150,5 +150,5 @@ function test() {
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_changes.js";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_highlighter.js b/browser/devtools/inspector/test/browser_inspector_highlighter.js
index 8537bf0415f..44ea73dd831 100644
--- a/browser/devtools/inspector/test/browser_inspector_highlighter.js
+++ b/browser/devtools/inspector/test/browser_inspector_highlighter.js
@@ -51,7 +51,6 @@ function createDocument() {
     inspector = aInspector;
     inspector.selection.setNode(div, null);
     inspector.once("inspector-updated", () => {
-      getHighlighterOutline().setAttribute("disable-transitions", "true");
       inspector.toolbox.highlighterUtils.startPicker().then(testMouseOverH1Highlights);
     });
   });
@@ -127,5 +126,5 @@ function test() {
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_highlighter.js";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_iframeTest.js b/browser/devtools/inspector/test/browser_inspector_iframeTest.js
index 2cc3be2df01..2a30facba78 100644
--- a/browser/devtools/inspector/test/browser_inspector_iframeTest.js
+++ b/browser/devtools/inspector/test/browser_inspector_iframeTest.js
@@ -31,6 +31,7 @@ function createDocument() {
       div2 = iframe2.contentDocument.createElement('div');
       div2.textContent = 'nested div';
       iframe2.contentDocument.body.appendChild(div2);
+
       // Open the inspector, start the picker mode, and start the tests
       openInspector(aInspector => {
         inspector = aInspector;
diff --git a/browser/devtools/inspector/test/browser_inspector_initialization.js b/browser/devtools/inspector/test/browser_inspector_initialization.js
index 6b0c59fceaa..2bccf0750b0 100644
--- a/browser/devtools/inspector/test/browser_inspector_initialization.js
+++ b/browser/devtools/inspector/test/browser_inspector_initialization.js
@@ -137,5 +137,5 @@ function test()
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_initialization.js";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_invalidate.js b/browser/devtools/inspector/test/browser_inspector_invalidate.js
index 13e4c4622ed..a78c3b71028 100644
--- a/browser/devtools/inspector/test/browser_inspector_invalidate.js
+++ b/browser/devtools/inspector/test/browser_inspector_invalidate.js
@@ -49,5 +49,5 @@ function test() {
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_invalidate.js";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_sidebarstate.js b/browser/devtools/inspector/test/browser_inspector_sidebarstate.js
index 09acfad3b15..4612c5191fa 100644
--- a/browser/devtools/inspector/test/browser_inspector_sidebarstate.js
+++ b/browser/devtools/inspector/test/browser_inspector_sidebarstate.js
@@ -67,5 +67,5 @@ function test()
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_sidebarstate.js";
 }
diff --git a/browser/devtools/inspector/test/browser_inspector_tree_height.js b/browser/devtools/inspector/test/browser_inspector_tree_height.js
index f234b62baf2..503c4a18bb2 100644
--- a/browser/devtools/inspector/test/browser_inspector_tree_height.js
+++ b/browser/devtools/inspector/test/browser_inspector_tree_height.js
@@ -106,6 +106,6 @@ function test()
     waitForFocus(createDocument, content);
   }, true);
 
-  content.location = "data:text/html,basic tests for inspector";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_tree_height.js";
 }
 
diff --git a/browser/devtools/inspector/test/head.js b/browser/devtools/inspector/test/head.js
index c39d68d48d6..c172ac0bd75 100644
--- a/browser/devtools/inspector/test/head.js
+++ b/browser/devtools/inspector/test/head.js
@@ -28,7 +28,7 @@ let testDir = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
 Services.scriptloader.loadSubScript(testDir + "../../../commandline/test/helpers.js", this);
 
 SimpleTest.registerCleanupFunction(() => {
-  console.error("Here we are\n")
+  console.error("Here we are\n");
   let {DebuggerServer} = Cu.import("resource://gre/modules/devtools/dbg-server.jsm", {});
   console.error("DebuggerServer open connections: " + Object.getOwnPropertyNames(DebuggerServer._connections).length);
 
diff --git a/browser/devtools/markupview/test/browser_inspector_markup_968316_highlight_node_after_mouseleave_mousemove.js b/browser/devtools/markupview/test/browser_inspector_markup_968316_highlight_node_after_mouseleave_mousemove.js
index 19879c0b57e..92b20bb013b 100644
--- a/browser/devtools/markupview/test/browser_inspector_markup_968316_highlight_node_after_mouseleave_mousemove.js
+++ b/browser/devtools/markupview/test/browser_inspector_markup_968316_highlight_node_after_mouseleave_mousemove.js
@@ -15,7 +15,7 @@ function test() {
     waitForFocus(startTests, content);
   }, true);
 
-  content.location = "data:text/html,<p>Select me!</p>";
+  content.location = "data:text/html;charset=utf-8,<p>Select me!</p>";
 }
 
 function startTests(aInspector, aToolbox) {
diff --git a/browser/devtools/markupview/test/browser_inspector_markup_968316_highlit_node_on_hover_then_select.js b/browser/devtools/markupview/test/browser_inspector_markup_968316_highlit_node_on_hover_then_select.js
index 0256cc57b0f..ccea1714d3a 100644
--- a/browser/devtools/markupview/test/browser_inspector_markup_968316_highlit_node_on_hover_then_select.js
+++ b/browser/devtools/markupview/test/browser_inspector_markup_968316_highlit_node_on_hover_then_select.js
@@ -15,7 +15,7 @@ function test() {
     waitForFocus(startTests, content);
   }, true);
 
-  content.location = "data:text/html,<p>It's going to be legen....</p>";
+  content.location = "data:text/html;charset=utf-8,<p>It's going to be legen....</p>";
 }
 
 function startTests(aInspector, aToolbox) {
diff --git a/browser/devtools/styleinspector/test/browser_ruleview_inherit.js b/browser/devtools/styleinspector/test/browser_ruleview_inherit.js
index e0ce0307d9e..bea78aace1a 100644
--- a/browser/devtools/styleinspector/test/browser_ruleview_inherit.js
+++ b/browser/devtools/styleinspector/test/browser_ruleview_inherit.js
@@ -112,5 +112,5 @@ function test()
     waitForFocus(() => openRuleView(simpleInherit), content);
   }, true);
 
-  content.location = "data:text/html,basic style inspector tests";
+  content.location = "data:text/html;charset=utf-8,browser_inspector_changes.js";
 }
diff --git a/browser/devtools/styleinspector/test/browser_ruleview_manipulation.js b/browser/devtools/styleinspector/test/browser_ruleview_manipulation.js
index a9e4f7cb223..f2c5f5bd2e3 100644
--- a/browser/devtools/styleinspector/test/browser_ruleview_manipulation.js
+++ b/browser/devtools/styleinspector/test/browser_ruleview_manipulation.js
@@ -83,5 +83,5 @@ function test()
     waitForFocus(() => openRuleView(simpleOverride), content);
   }, true);
 
-  content.location = "data:text/html,basic style inspector tests";
+  content.location = "data:text/html;charset=utf-8,browser_ruleview_manipulation.js";
 }
diff --git a/browser/devtools/styleinspector/test/browser_ruleview_override.js b/browser/devtools/styleinspector/test/browser_ruleview_override.js
index 6cb695d09a9..89607e1969c 100644
--- a/browser/devtools/styleinspector/test/browser_ruleview_override.js
+++ b/browser/devtools/styleinspector/test/browser_ruleview_override.js
@@ -178,5 +178,5 @@ function test()
     waitForFocus(() => openRuleView(simpleOverride), content);
   }, true);
 
-  content.location = "data:text/html,basic style inspector tests";
+  content.location = "data:text/html;charset=utf-8,browser_ruleview_override.js";
 }
diff --git a/browser/devtools/styleinspector/test/browser_ruleview_ui.js b/browser/devtools/styleinspector/test/browser_ruleview_ui.js
index c4764fd20e1..c13f2dcc74e 100644
--- a/browser/devtools/styleinspector/test/browser_ruleview_ui.js
+++ b/browser/devtools/styleinspector/test/browser_ruleview_ui.js
@@ -248,5 +248,5 @@ function test()
     waitForFocus(() => openRuleView(startTest), content);
   }, true);
 
-  content.location = "data:text/html,basic style inspector tests";
+  content.location = "data:text/html;charset=utf-8,browser_ruleview_ui.js";
 }
diff --git a/browser/devtools/styleinspector/test/browser_ruleview_update.js b/browser/devtools/styleinspector/test/browser_ruleview_update.js
index 540005bcaf0..59d5fc460e3 100644
--- a/browser/devtools/styleinspector/test/browser_ruleview_update.js
+++ b/browser/devtools/styleinspector/test/browser_ruleview_update.js
@@ -189,5 +189,5 @@ function test()
     waitForFocus(() => openRuleView(startTest), content);
   }, true);
 
-  content.location = "data:text/html,basic style inspector tests";
+  content.location = "data:text/html;charset=utf-8,browser_ruleview_update.js";
 }
diff --git a/browser/devtools/webconsole/test/browser_webconsole_output_03.js b/browser/devtools/webconsole/test/browser_webconsole_output_03.js
index fe606d13a7d..073981e3c5c 100644
--- a/browser/devtools/webconsole/test/browser_webconsole_output_03.js
+++ b/browser/devtools/webconsole/test/browser_webconsole_output_03.js
@@ -153,7 +153,6 @@ let inputTests = [
 ];
 
 function test() {
-
   addTab(TEST_URI);
   browser.addEventListener("load", function onLoad() {
     browser.removeEventListener("load", onLoad, true);
diff --git a/browser/devtools/webconsole/test/browser_webconsole_view_source.js b/browser/devtools/webconsole/test/browser_webconsole_view_source.js
index 645599a2c09..d52a0b65267 100644
--- a/browser/devtools/webconsole/test/browser_webconsole_view_source.js
+++ b/browser/devtools/webconsole/test/browser_webconsole_view_source.js
@@ -28,7 +28,7 @@ function testViewSource(hud) {
   EventUtils.sendMouseEvent({ type: "click" }, button, content);
 
   openDebugger().then(({panelWin: { DebuggerView }}) => {
-    info("debugger openeed");
+    info("debugger opened");
     Sources = DebuggerView.Sources;
     openConsole(null, (hud) => {
       info("console opened again");