Enable the ESLint `no-var` rule in the `src/core/type1_parser.js` file
Enable the ESLint `no-var` rule in the `src/core/type1_parser.js` file

Note that the majority of these changes were done automatically, by using `gulp lint --fix`, and the manual changes were limited to the following diff:

```diff
diff --git a/src/core/type1_parser.js b/src/core/type1_parser.js
index 192781de1..05c5fe2e5 100644
--- a/src/core/type1_parser.js
+++ b/src/core/type1_parser.js
@@ -251,7 +251,7 @@ const Type1CharString = (function Type1CharStringClosure() {
               // vhea tables reconstruction -- ignoring it.
               this.stack.pop(); // wy
               wx = this.stack.pop();
-              var sby = this.stack.pop();
+              const sby = this.stack.pop();
               sbx = this.stack.pop();
               this.lsb = sbx;
               this.width = wx;
@@ -263,8 +263,8 @@ const Type1CharString = (function Type1CharStringClosure() {
                 error = true;
                 break;
               }
-              var num2 = this.stack.pop();
-              var num1 = this.stack.pop();
+              const num2 = this.stack.pop();
+              const num1 = this.stack.pop();
               this.stack.push(num1 / num2);
               break;
             case (12 << 8) + 16: // callothersubr
@@ -273,7 +273,7 @@ const Type1CharString = (function Type1CharStringClosure() {
                 break;
               }
               subrNumber = this.stack.pop();
-              var numArgs = this.stack.pop();
+              const numArgs = this.stack.pop();
               if (subrNumber === 0 && numArgs === 3) {
                 const flexArgs = this.stack.splice(this.stack.length - 17, 17);
                 this.stack.push(
@@ -397,9 +397,9 @@ const Type1Parser = (function Type1ParserClosure() {
     if (discardNumber >= data.length) {
       return new Uint8Array(0);
     }
+    const c1 = 52845,
+      c2 = 22719;
     let r = key | 0,
-      c1 = 52845,
-      c2 = 22719,
       i,
       j;
     for (i = 0; i < discardNumber; i++) {
@@ -416,9 +416,9 @@ const Type1Parser = (function Type1ParserClosure() {
   }

   function decryptAscii(data, key, discardNumber) {
-    let r = key | 0,
-      c1 = 52845,
+    const c1 = 52845,
       c2 = 22719;
+    let r = key | 0;
     const count = data.length,
       maybeLength = count >>> 1;
     const decrypted = new Uint8Array(maybeLength);
@@ -429,7 +429,7 @@ const Type1Parser = (function Type1ParserClosure() {
         continue;
       }
       i++;
-      var digit2;
+      let digit2;
       while (i < count && !isHexDigit((digit2 = data[i]))) {
         i++;
       }
@@ -599,7 +599,7 @@ const Type1Parser = (function Type1ParserClosure() {
               if (token !== "/") {
                 continue;
               }
-              var glyph = this.getToken();
+              const glyph = this.getToken();
               length = this.readInt();
               this.getToken(); // read in 'RD' or '-|'
               data = length > 0 ? stream.getBytes(length) : new Uint8Array(0);
@@ -638,7 +638,7 @@ const Type1Parser = (function Type1ParserClosure() {
           case "OtherBlues":
           case "FamilyBlues":
           case "FamilyOtherBlues":
-            var blueArray = this.readNumberArray();
+            const blueArray = this.readNumberArray();
             // *Blue* values may contain invalid data: disables reading of
             // those values when hinting is disabled.
             if (
@@ -672,7 +672,7 @@ const Type1Parser = (function Type1ParserClosure() {
       }

       for (let i = 0; i < charstrings.length; i++) {
-        glyph = charstrings[i].glyph;
+        const glyph = charstrings[i].glyph;
         encoded = charstrings[i].encoded;
         const charString = new Type1CharString();
         const error = charString.convert(
@@ -728,12 +728,12 @@ const Type1Parser = (function Type1ParserClosure() {
         token = this.getToken();
         switch (token) {
           case "FontMatrix":
-            var matrix = this.readNumberArray();
+            const matrix = this.readNumberArray();
             properties.fontMatrix = matrix;
             break;
           case "Encoding":
-            var encodingArg = this.getToken();
-            var encoding;
+            const encodingArg = this.getToken();
+            let encoding;
             if (!/^\d+$/.test(encodingArg)) {
               // encoding name is specified
               encoding = getEncoding(encodingArg);
@@ -764,7 +764,7 @@ const Type1Parser = (function Type1ParserClosure() {
             properties.builtInEncoding = encoding;
             break;
           case "FontBBox":
-            var fontBBox = this.readNumberArray();
+            const fontBBox = this.readNumberArray();
             // adjusting ascent/descent
             properties.ascent = Math.max(fontBBox[3], fontBBox[1]);
             properties.descent = Math.min(fontBBox[1], fontBBox[3]);
```

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