Devtools: Fix "unable to change the value of R/G/B/A" in color picker

Source/devtools/front_end/elements/Spectrum.js

Index: Source/devtools/front_end/elements/Spectrum.js
diff --git a/Source/devtools/front_end/elements/Spectrum.js b/Source/devtools/front_end/elements/Spectrum.js
index f9cc1b59e09bb23a550e75016ba6af7bf83e9c11..5ff38b8f7299f9518efb9603387d6678a3ce66fe 100644
--- a/Source/devtools/front_end/elements/Spectrum.js
+++ b/Source/devtools/front_end/elements/Spectrum.js
@@ -313,8 +313,17 @@ WebInspector.Spectrum.prototype = {
             return element.value;
         }
 
-        var element = /** @type {!Element} */(event.currentTarget);
-        WebInspector.handleElementValueModifications(event, element);
+        var inputElement = /** @type {!Element} */(event.currentTarget);
+        var arrowKeyOrMouseWheelEvent = (event.keyIdentifier === "Up" || event.keyIdentifier === "Down" || event.type === "mousewheel");
+        var pageKeyPressed = (event.keyIdentifier === "PageUp" || event.keyIdentifier === "PageDown");
+        if (arrowKeyOrMouseWheelEvent || pageKeyPressed) {
+            var newValue = WebInspector.createReplacementString(inputElement.value, event);
+            if (newValue) {
+                inputElement.value = newValue;
+                inputElement.selectionStart = 0;
+                inputElement.selectionEnd = newValue.length;
+            }
+        }
 
         const cf = WebInspector.Color.Format;
         var colorString;