Use the const keyword for constants in src/shared/util.js

Moreover, move general constants to the top of the file, i.e., those
that are not closely tied to a function in the file.

src/shared/util.js

@@ -17,7 +17,8 @@ import './compatibility';
 import { ReadableStream } from './streams_polyfill';
 import { URL } from './url_polyfill';
 
-var FONT_IDENTITY_MATRIX = [0.001, 0, 0, 0.001, 0, 0];
+const IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
+const FONT_IDENTITY_MATRIX = [0.001, 0, 0, 0.001, 0, 0];
 
 const NativeImageDecoding = {
   NONE: 'none',
@@ -37,7 +38,7 @@ const PermissionFlag = {
   PRINT_HIGH_QUALITY: 0x800,
 };
 
-var TextRenderingMode = {
+const TextRenderingMode = {
   FILL: 0,
   STROKE: 1,
   FILL_STROKE: 2,
@@ -50,13 +51,13 @@ var TextRenderingMode = {
   ADD_TO_PATH_FLAG: 4,
 };
 
-var ImageKind = {
+const ImageKind = {
   GRAYSCALE_1BPP: 1,
   RGB_24BPP: 2,
   RGBA_32BPP: 3,
 };
 
-var AnnotationType = {
+const AnnotationType = {
   TEXT: 1,
   LINK: 2,
   FREETEXT: 3,
@@ -85,7 +86,7 @@ var AnnotationType = {
   REDACT: 26,
 };
 
-var AnnotationFlag = {
+const AnnotationFlag = {
   INVISIBLE: 0x01,
   HIDDEN: 0x02,
   PRINT: 0x04,
@@ -98,7 +99,7 @@ var AnnotationFlag = {
   LOCKEDCONTENTS: 0x200,
 };
 
-var AnnotationFieldFlag = {
+const AnnotationFieldFlag = {
   READONLY: 0x0000001,
   REQUIRED: 0x0000002,
   NOEXPORT: 0x0000004,
@@ -120,15 +121,15 @@ var AnnotationFieldFlag = {
   COMMITONSELCHANGE: 0x4000000,
 };
 
-var AnnotationBorderStyleType = {
+const AnnotationBorderStyleType = {
   SOLID: 1,
   DASHED: 2,
   BEVELED: 3,
   INSET: 4,
   UNDERLINE: 5,
 };
 
-var StreamType = {
+const StreamType = {
   UNKNOWN: 0,
   FLATE: 1,
   LZW: 2,
@@ -141,7 +142,7 @@ var StreamType = {
   RL: 9,
 };
 
-var FontType = {
+const FontType = {
   UNKNOWN: 0,
   TYPE1: 1,
   TYPE1C: 2,
@@ -161,14 +162,14 @@ const VerbosityLevel = {
   INFOS: 5,
 };
 
-var CMapCompressionType = {
+const CMapCompressionType = {
   NONE: 0,
   BINARY: 1,
   STREAM: 2,
 };
 
 // All the possible operations for an operator list.
-var OPS = {
+const OPS = {
   // Intentionally start from 1 so it is easy to spot bad operators that will be
   // 0's.
   dependency: 1,
@@ -264,6 +265,20 @@ var OPS = {
   constructPath: 91,
 };
 
+const UNSUPPORTED_FEATURES = {
+  unknown: 'unknown',
+  forms: 'forms',
+  javaScript: 'javaScript',
+  smask: 'smask',
+  shadingPattern: 'shadingPattern',
+  font: 'font',
+};
+
+const PasswordResponses = {
+  NEED_PASSWORD: 1,
+  INCORRECT_PASSWORD: 2,
+};
+
 let verbosity = VerbosityLevel.WARNINGS;
 
 function setVerbosityLevel(level) {
@@ -307,15 +322,6 @@ function assert(cond, msg) {
   }
 }
 
-var UNSUPPORTED_FEATURES = {
-  unknown: 'unknown',
-  forms: 'forms',
-  javaScript: 'javaScript',
-  smask: 'smask',
-  shadingPattern: 'shadingPattern',
-  font: 'font',
-};
-
 // Checks if URLs have the same origin. For non-HTTP based URLs, returns false.
 function isSameOrigin(baseUrl, otherUrl) {
   try {
@@ -388,11 +394,6 @@ function getLookupTableFactory(initializer) {
   };
 }
 
-var PasswordResponses = {
-  NEED_PASSWORD: 1,
-  INCORRECT_PASSWORD: 2,
-};
-
 var PasswordException = (function PasswordExceptionClosure() {
   function PasswordException(msg, code) {
     this.name = 'PasswordException';
@@ -693,8 +694,6 @@ function getInheritableProperty({ dict, key, getArray = false,
   return values;
 }
 
-var IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
-
 var Util = (function UtilClosure() {
   function Util() {}
 
@@ -892,7 +891,7 @@ function toRomanNumerals(number, lowerCase = false) {
   return (lowerCase ? romanStr.toLowerCase() : romanStr);
 }
 
-var PDFStringTranslateTable = [
+const PDFStringTranslateTable = [
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0x2D8, 0x2C7, 0x2C6, 0x2D9, 0x2DD, 0x2DB, 0x2DA, 0x2DC, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,