[DevTools] Initial implementation of device modes.

Source/devtools/front_end/emulation/overrides.css

Index: Source/devtools/front_end/emulation/overrides.css
diff --git a/Source/devtools/front_end/emulation/overrides.css b/Source/devtools/front_end/emulation/overrides.css
index a8254a6db591dd0860d6ddf21684fd401c612fd0..58de08c1e9b0681247380858866604dab63e262e 100644
--- a/Source/devtools/front_end/emulation/overrides.css
+++ b/Source/devtools/front_end/emulation/overrides.css
@@ -142,10 +142,19 @@
 }
 
 .overrides-device .overrides-device-model-section select {
-    width: 244px;
     height: 20px;
 }
 
+.overrides-device .overrides-device-model-section select.device-select {
+    width: 180px;
+    margin-right: 6px;
+}
+
+.overrides-device .overrides-device-model-section .mode-container {
+    display: inline-block;
+    width: 140px;
+}
+
 /* Media tab */
 
 .overrides-media > label {
@@ -198,7 +207,7 @@
 }
 
 .overrides-view input[type=text] {
-    margin: 0;
+    margin-left: 3px;
     min-height: 2em;
     padding: 3px;
 }