[api-minor] Remove the CMapCompressionType enumeration

After the binary CMap format had been added there were also some ideas about *maybe* providing other formats, see [here](https://github.com/mozilla/pdf.js/pull/8064#issuecomment-279730182), however that was over seven years ago and we still only use binary CMaps.
Hence it now seems reasonable to simplify the relevant code by removing `CMapCompressionType` and instead just use a boolean to indicate the type of the built-in CMaps.

src/core/cmap.js

@@ -13,13 +13,8 @@
  * limitations under the License.
  */
 
-import {
-  CMapCompressionType,
-  FormatError,
-  unreachable,
-  warn,
-} from "../shared/util.js";
 import { Cmd, EOF, isCmd, Name } from "./primitives.js";
+import { FormatError, unreachable, warn } from "../shared/util.js";
 import { BaseStream } from "./base_stream.js";
 import { BinaryCMapReader } from "./binary_cmap.js";
 import { Lexer } from "./parser.js";
@@ -687,19 +682,16 @@ async function createBuiltInCMap(name, fetchBuiltInCMap) {
     throw new Error("Built-in CMap parameters are not provided.");
   }
 
-  const { cMapData, compressionType } = await fetchBuiltInCMap(name);
+  const { cMapData, isCompressed } = await fetchBuiltInCMap(name);
   const cMap = new CMap(true);
 
-  if (compressionType === CMapCompressionType.BINARY) {
+  if (isCompressed) {
     return new BinaryCMapReader().process(cMapData, cMap, useCMap =>
       extendCMap(cMap, fetchBuiltInCMap, useCMap)
     );
   }
-  if (compressionType === CMapCompressionType.NONE) {
-    const lexer = new Lexer(new Stream(cMapData));
-    return parseCMap(cMap, lexer, fetchBuiltInCMap, null);
-  }
-  throw new Error(`Invalid CMap "compressionType" value: ${compressionType}`);
+  const lexer = new Lexer(new Stream(cMapData));
+  return parseCMap(cMap, lexer, fetchBuiltInCMap, null);
 }
 
 class CMapFactory {

src/core/evaluator.js

@@ -17,7 +17,6 @@
 import {
   AbortException,
   assert,
-  CMapCompressionType,
   FONT_IDENTITY_MATRIX,
   FormatError,
   IDENTITY_MATRIX,
@@ -392,7 +391,7 @@ class PartialEvaluator {
       }
       data = {
         cMapData: new Uint8Array(await response.arrayBuffer()),
-        compressionType: CMapCompressionType.BINARY,
+        isCompressed: true,
       };
     } else {
       // Get the data on the main-thread instead.

src/display/base_factory.js

@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-import { CMapCompressionType, unreachable } from "../shared/util.js";
+import { unreachable } from "../shared/util.js";
 
 class BaseFilterFactory {
   constructor() {
@@ -129,12 +129,7 @@ class BaseCMapReaderFactory {
     const url = this.baseUrl + name + (this.isCompressed ? ".bcmap" : "");
 
     return this._fetch(url)
-      .then(cMapData => ({
-        cMapData,
-        compressionType: this.isCompressed
-          ? CMapCompressionType.BINARY
-          : CMapCompressionType.NONE,
-      }))
+      .then(cMapData => ({ cMapData, isCompressed: this.isCompressed }))
       .catch(reason => {
         throw new Error(
           `Unable to load ${this.isCompressed ? "binary " : ""}CMap at: ${url}`

src/pdf.js

@@ -27,7 +27,6 @@ import {
   AnnotationEditorParamsType,
   AnnotationEditorType,
   AnnotationMode,
-  CMapCompressionType,
   createValidAbsoluteUrl,
   FeatureTest,
   ImageKind,
@@ -96,7 +95,6 @@ export {
   AnnotationLayer,
   AnnotationMode,
   build,
-  CMapCompressionType,
   ColorPicker,
   createValidAbsoluteUrl,
   DOMSVGFactory,

src/shared/util.js

@@ -240,11 +240,6 @@ const VerbosityLevel = {
   INFOS: 5,
 };
 
-const CMapCompressionType = {
-  NONE: 0,
-  BINARY: 1,
-};
-
 // All the possible operations for an operator list.
 const OPS = {
   // Intentionally start from 1 so it is easy to spot bad operators that will be
@@ -1119,7 +1114,6 @@ export {
   BaseException,
   BASELINE_FACTOR,
   bytesToString,
-  CMapCompressionType,
   createValidAbsoluteUrl,
   DocumentActionEventType,
   FeatureTest,