DevTools: allow editing custom color palette, move it out of experimental.

Source/devtools/front_end/elements/spectrum.css

Index: Source/devtools/front_end/elements/spectrum.css
diff --git a/Source/devtools/front_end/elements/spectrum.css b/Source/devtools/front_end/elements/spectrum.css
index 6d5b965762dc85838170814472d53b46fc344dc9..5eaadb7f3a742513b88d8bdddf847b620cf2dbb3 100644
--- a/Source/devtools/front_end/elements/spectrum.css
+++ b/Source/devtools/front_end/elements/spectrum.css
@@ -88,12 +88,12 @@
 }
 
 .swatch {
-    width: 16px;
-    height: 16px;
+    width: 24px;
+    height: 24px;
     margin: 0;
     position: absolute;
-    top: 148px;
-    left: 48px;
+    top: 144px;
+    left: 47px;
     background-image: url(Images/checker.png);
     border-radius: 16px;
 }
@@ -190,27 +190,28 @@
     position: absolute;
     top: 235px;
     width: 100%;
-    padding-right: 24px;
+    padding: 6px 24px 6px 6px;
     display: flex;
     flex-wrap: wrap;
 }
 
 .spectrum-palette-color {
+    width: 12px;
     height: 12px;
     flex: 0 0 12px;
     display: inline-block;
     border-radius: 2px;
-    margin-left: 12px;
-    margin-top: 12px;
+    margin: 6px;
     cursor: pointer;
 }
 
-.spectrum-palette-color.empty-color {
-    border: 1px solid #dadada;
-}
-
 .spectrum-palette > .spectrum-palette-color {
     transition: transform 100ms cubic-bezier(0, 0, 0.2, 1);
+    border: 1px solid rgba(0, 0, 0, 0.1);
+}
+
+.spectrum-palette > .spectrum-palette-color.empty-color {
+    border-color: transparent;
 }
 
 .spectrum-palette > .spectrum-palette-color:not(.empty-color):hover {
@@ -218,8 +219,7 @@
 }
 
 .spectrum-palette > .toolbar {
-    margin-left: 5px;
-    margin-top: 5px;
+    margin-top: -2px;
 }
 
 .spectrum-palette-switcher {