Remove the "Page: " label and replace it with a tooltip

The following reasoning was used for deciding to remove the "Page: " label, and replace it with a tooltip, from the main toolbar:
 - We have no other visible labels in the *main* toolbar (e.g. the Zoom dropdown doesn't have a label, but only a tooltip).
 - We already hide the "Page: " label when the viewer is narrow.
 - The varying width of the "Page: " label in different locales is already causing issues for many languages, with overlap in the main toolbar as a result.
Trying to create responsive CSS styles that works well in all locales is already difficult, and if we add support for page labels that will only further compound the issues.
 - Some PDF viewers (e.g. Adobe Reader, pdfium in Chrome) doesn't show labels in the UI by default.

l10n/en-US/viewer.properties

@@ -18,11 +18,10 @@ previous_label=Previous
 next.title=Next Page
 next_label=Next
 
-# LOCALIZATION NOTE (page_label, page_of):
-# These strings are concatenated to form the "Page: X of Y" string.
-# Do not translate "{{pageCount}}", it will be substituted with a number
-# representing the total number of pages.
-page_label=Page:
+# LOCALIZATION NOTE (page.title): The tooltip for the pageNumber input.
+page.title=Page
+# LOCALIZATION NOTE (page_of): "{{pageCount}}" will be replaced by a number
+# representing the total number of pages in the document.
 page_of=of {{pageCount}}
 
 zoom_out.title=Zoom Out

l10n/sv-SE/viewer.properties

@@ -18,11 +18,10 @@ previous_label=Föregående
 next.title=Nästa sida
 next_label=Nästa
 
-# LOCALIZATION NOTE (page_label, page_of):
-# These strings are concatenated to form the "Page: X of Y" string.
-# Do not translate "{{pageCount}}", it will be substituted with a number
-# representing the total number of pages.
-page_label=Sida:
+# LOCALIZATION NOTE (page.title): The tooltip for the pageNumber input.
+page.title=Sida
+# LOCALIZATION NOTE (page_of): "{{pageCount}}" will be replaced by a number
+# representing the total number of pages in the document.
 page_of=av {{pageCount}}
 
 zoom_out.title=Zooma ut

web/viewer.css

@@ -1939,7 +1939,7 @@ html[dir='rtl'] #documentPropertiesOverlay .row > * {
 }
 
 @media all and (max-width: 510px) {
-  #scaleSelectContainer, #pageNumberLabel {
+  #scaleSelectContainer {
     display: none;
   }
 }

web/viewer.html

@@ -194,8 +194,7 @@ See https://github.com/adobe-type-tools/cmap-resources
                     <span data-l10n-id="next_label">Next</span>
                   </button>
                 </div>
-                <label id="pageNumberLabel" class="toolbarLabel" for="pageNumber" data-l10n-id="page_label">Page: </label>
-                <input type="number" id="pageNumber" class="toolbarField pageNumber" value="1" size="4" min="1" tabindex="15">
+                <input type="number" id="pageNumber" class="toolbarField pageNumber" title="Page" value="1" size="4" min="1" tabindex="15" data-l10n-id="page">
                 <span id="numPages" class="toolbarLabel"></span>
               </div>
               <div id="toolbarViewerRight">
@@ -236,7 +235,7 @@ See https://github.com/adobe-type-tools/cmap-resources
                      </button>
                   </div>
                   <span id="scaleSelectContainer" class="dropdownToolbarButton">
-                     <select id="scaleSelect" title="Zoom" tabindex="23" data-l10n-id="zoom">
+                    <select id="scaleSelect" title="Zoom" tabindex="23" data-l10n-id="zoom">
                       <option id="pageAutoOption" title="" value="auto" selected="selected" data-l10n-id="page_scale_auto">Automatic Zoom</option>
                       <option id="pageActualOption" title="" value="page-actual" data-l10n-id="page_scale_actual">Actual Size</option>
                       <option id="pageFitOption" title="" value="page-fit" data-l10n-id="page_scale_fit">Fit Page</option>