Revert of Devtools: Cut color picker off at bottom instead of the top (patchset #1 id:1 of https://codereview.chromium.org/1816933002/ )

Reason for revert:
Breaks color picker with no easy fix: crbug.com/603811

Original issue's description:
> Devtools: Cut color picker off at bottom instead of the top
>
> When there is insufficent vertical space, the color picker is cut off at
> the top. This change fixes it at the top in these situations, allowing
> better usability of the color picker in these states.
>
> BUG=572101
>
> Committed: https://crrev.com/acc1963c73bc1e4dabf926d5f99d9323d2918016
> Cr-Commit-Position: refs/heads/master@{#386581}

[email protected]
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=572101

Review URL: https://codereview.chromium.org/1900033002

Cr-Commit-Position: refs/heads/master@{#388127}

Author: lisamuel

front_end/elements/spectrum.css

@@ -3,8 +3,6 @@
     width: 232px;
     height: 240px;
     -webkit-user-select: none;
-    /* Prevents the popover from jumping when focus() is called */
-    display: block !important;
 }
 
 :host(.palettes-enabled) {

front_end/ui/Popover.js

@@ -243,7 +243,7 @@ WebInspector.Popover.prototype = {
         }
 
         this.element.className = WebInspector.Popover._classNamePrefix + " " + verticalAlignment + "-" + horizontalAlignment + "-arrow";
-        this.element.positionAt(newElementPosition.x, Math.max(0, newElementPosition.y - borderWidth), container);
+        this.element.positionAt(newElementPosition.x, newElementPosition.y - borderWidth, container);
         this.element.style.width = newElementPosition.width + borderWidth * 2 + "px";
         this.element.style.height = newElementPosition.height + borderWidth * 2 + "px";
     },