[DevTools] Fix various bugs in Device Mode.

third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css

Index: third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css
diff --git a/third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css b/third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css
index 31bd4168ca4352634e5c8987460190287037ba3d..cf00646e1d482de55dc30dbf7491bbe128fd75d8 100644
--- a/third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css
+++ b/third_party/WebKit/Source/devtools/front_end/emulation/deviceModeView.css
@@ -22,14 +22,19 @@
 
 .device-mode-toolbar .toolbar {
     overflow: hidden;
-    flex: none;
+    flex: 0 100000 auto;
     padding: 0 5px;
 }
 
+.device-mode-toolbar .toolbar.device-mode-toolbar-fixed-size {
+    flex: 0 1 auto;
+}
+
 .device-mode-toolbar-spacer {
     flex: 1 1 0;
     display: flex;
     flex-direction: row;
+    overflow: hidden;
 }
 
 .device-mode-content-clip {
@@ -133,6 +138,7 @@
     display: flex;
     align-items: center;
     justify-content: center;
+    overflow: hidden;
     transition: background-color 0.1s ease;
 }