Update patchset selector styles

Also fixed patchset dropdown so that 'edit' does not display as
'Patchset edit'

Change-Id: I14f02f878d0e459644511cebfd3a2208cfd2e053

polygerrit-ui/app/elements/diff/gr-patch-range-select/gr-patch-range-select.html

@@ -32,8 +32,17 @@ limitations under the License.
         max-width: 15em;
       }
       .arrow {
+        color: rgba(0,0,0,.7);
         margin: 0 .5em;
       }
+      gr-dropdown-list {
+        --trigger-style: {
+          color: rgba(0,0,0,.7);
+          text-transform: none;
+          font-family: var(--font-family);
+        }
+        --trigger-hover-color: rgba(0,0,0,.6);
+      }
       @media screen and (max-width: 50em) {
         .filesWeblinks {
           display: none;

polygerrit-ui/app/elements/diff/gr-patch-range-select/gr-patch-range-select.js

@@ -102,8 +102,9 @@
         dropdownContent.push({
           disabled: this._computeRightDisabled(patchNum, basePatchNum,
               _sortedRevisions),
-          triggerText: `Patchset ${patchNum}`,
-          text: `Patchset ${patchNum}` +
+          triggerText: `${patchNum === 'edit' ? '': 'Patchset '}` +
+              patchNum,
+          text: `${patchNum === 'edit' ? '': 'Patchset '}${patchNum}` +
               `${this._computePatchSetCommentsString(
                   this.comments, patchNum)}`,
           mobileText: this._computeMobileText(patchNum, this.comments,

polygerrit-ui/app/elements/diff/gr-patch-range-select/gr-patch-range-select_test.html

@@ -246,8 +246,8 @@ limitations under the License.
         },
         {
           disabled: false,
-          triggerText: 'Patchset edit',
-          text: 'Patchset edit',
+          triggerText: 'edit',
+          text: 'edit',
           mobileText: 'edit',
           bottomText: '',
           value: 'edit',