Enable the no-else-return ESLint rule

Using `else` after `return` is not necessary, and can often lead to unnecessarily cluttered code. By using the `no-else-return` rule in ESLint we can avoid this pattern, see http://eslint.org/docs/rules/no-else-return.

web/compatibility.js

@@ -202,9 +202,8 @@ if (typeof PDFJS === 'undefined') {
       get: function xmlHttpRequestResponseGet() {
         if (this.responseType === 'arraybuffer') {
           return new Uint8Array(new VBArray(this.responseBody).toArray());
-        } else {
-          return this.responseText;
         }
+        return this.responseText;
       }
     });
     return;

web/pdf_document_properties.js

@@ -178,12 +178,11 @@ var PDFDocumentProperties = (function PDFDocumentPropertiesClosure() {
           size_kb: (+kb.toPrecision(3)).toLocaleString(),
           size_b: fileSize.toLocaleString()
         }, '{{size_kb}} KB ({{size_b}} bytes)');
-      } else {
-        return mozL10n.get('document_properties_mb', {
-          size_mb: (+(kb / 1024).toPrecision(3)).toLocaleString(),
-          size_b: fileSize.toLocaleString()
-        }, '{{size_mb}} MB ({{size_b}} bytes)');
       }
+      return mozL10n.get('document_properties_mb', {
+        size_mb: (+(kb / 1024).toPrecision(3)).toLocaleString(),
+        size_b: fileSize.toLocaleString()
+      }, '{{size_mb}} MB ({{size_b}} bytes)');
     },
 
     /**

web/pdf_find_controller.js

@@ -399,22 +399,21 @@ var PDFFindController = (function PDFFindControllerClosure() {
         offset.matchIdx = (previous ? numMatches - 1 : 0);
         this.updateMatch(true);
         return true;
-      } else {
-        // No matches, so attempt to search the next page.
-        this.advanceOffsetPage(previous);
-        if (offset.wrapped) {
-          offset.matchIdx = null;
-          if (this.pagesToSearch < 0) {
-            // No point in wrapping again, there were no matches.
-            this.updateMatch(false);
-            // while matches were not found, searching for a page
-            // with matches should nevertheless halt.
-            return true;
-          }
-        }
-        // Matches were not found (and searching is not done).
-        return false;
       }
+      // No matches, so attempt to search the next page.
+      this.advanceOffsetPage(previous);
+      if (offset.wrapped) {
+        offset.matchIdx = null;
+        if (this.pagesToSearch < 0) {
+          // No point in wrapping again, there were no matches.
+          this.updateMatch(false);
+          // while matches were not found, searching for a page
+          // with matches should nevertheless halt.
+          return true;
+        }
+      }
+      // Matches were not found (and searching is not done).
+      return false;
     },
 
     /**

web/pdf_history.js

@@ -284,9 +284,8 @@
           this.nextHashParam = null;
           this.updatePreviousBookmark = true;
           return;
-        } else {
-          this.nextHashParam = null;
         }
+        this.nextHashParam = null;
       }
 
       if (params.hash) {

web/pdf_page_view.js

@@ -624,7 +624,7 @@ var PDFPageView = (function PDFPageViewClosure() {
           onRenderContinue: function (cont) { },
           cancel: function () { },
         };
-      } else {
+      } else { // eslint-disable-line no-else-return
         var cancelled = false;
         var ensureNotCancelled = function () {
           if (cancelled) {

web/pdf_viewer.js

@@ -833,14 +833,13 @@ var PDFViewer = (function pdfViewer() {
     _getVisiblePages: function () {
       if (!this.isInPresentationMode) {
         return getVisibleElements(this.container, this._pages, true);
-      } else {
-        // The algorithm in getVisibleElements doesn't work in all browsers and
-        // configurations when presentation mode is active.
-        var visible = [];
-        var currentPage = this._pages[this._currentPageNumber - 1];
-        visible.push({ id: currentPage.id, view: currentPage });
-        return { first: currentPage, last: currentPage, views: visible };
       }
+      // The algorithm in getVisibleElements doesn't work in all browsers and
+      // configurations when presentation mode is active.
+      var visible = [];
+      var currentPage = this._pages[this._currentPageNumber - 1];
+      visible.push({ id: currentPage.id, view: currentPage });
+      return { first: currentPage, last: currentPage, views: visible };
     },
 
     cleanup: function () {

web/ui_utils.js

@@ -280,12 +280,14 @@ function approximateFraction(x) {
       a = p; b = q;
     }
   }
+  var result;
   // Select closest of the neighbours to x.
   if (x_ - a / b < c / d - x_) {
-    return x_ === x ? [a, b] : [b, a];
+    result = x_ === x ? [a, b] : [b, a];
   } else {
-    return x_ === x ? [c, d] : [d, c];
+    result = x_ === x ? [c, d] : [d, c];
   }
+  return result;
 }
 
 function roundToDivide(x, div) {