Enable the ESLint no-var rule in the src/core/evaluator.js file

This was previously attempted in PR 13371, but had to be reverted because of issues related to SystemJS (which has since been removed).

Also, while unrelated, shortens an existing conditional assignment.

src/core/evaluator.js

@@ -12,7 +12,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* eslint-disable no-var */
 
 import {
   AbortException,
@@ -1887,7 +1886,7 @@ class PartialEvaluator {
             );
             return;
           case OPS.setFont:
-            var fontSize = args[1];
+            const fontSize = args[1];
             // eagerly collect all fonts
             next(
               self
@@ -1913,7 +1912,7 @@ class PartialEvaluator {
             parsingText = false;
             break;
           case OPS.endInlineImage:
-            var cacheKey = args[0].cacheKey;
+            const cacheKey = args[0].cacheKey;
             if (cacheKey) {
               const localImage = localImageCache.getByName(cacheKey);
               if (localImage) {
@@ -1946,8 +1945,8 @@ class PartialEvaluator {
               self.ensureStateFont(stateManager.state);
               continue;
             }
-            var combinedGlyphs = [];
-            var state = stateManager.state;
+            const combinedGlyphs = [],
+              state = stateManager.state;
             for (const arrItem of args[0]) {
               if (typeof arrItem === "string") {
                 combinedGlyphs.push(...self.handleText(arrItem, state));
@@ -3079,6 +3078,8 @@ class PartialEvaluator {
 
       const operation = {};
       let stop,
+        name,
+        isValidName,
         args = [];
       while (!(stop = timeSlotManager.check())) {
         // The arguments parsed by read() are not used beyond this loop, so
@@ -3098,7 +3099,7 @@ class PartialEvaluator {
         switch (fn | 0) {
           case OPS.setFont:
             // Optimization to ignore multiple identical Tf commands.
-            var fontNameArg = args[0].name,
+            const fontNameArg = args[0].name,
               fontSizeArg = args[1];
             if (
               textState.font &&
@@ -3239,12 +3240,10 @@ class PartialEvaluator {
             break;
           case OPS.paintXObject:
             flushTextContentItem();
-            if (!xobjs) {
-              xobjs = resources.get("XObject") || Dict.empty;
-            }
+            xobjs ??= resources.get("XObject") || Dict.empty;
 
-            var isValidName = args[0] instanceof Name;
-            var name = args[0].name;
+            isValidName = args[0] instanceof Name;
+            name = args[0].name;
 
             if (isValidName && emptyXObjectCache.getByName(name)) {
               break;