Fix regression with `important` filter option

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/1732

The regression affect filter with the `important` option when
the following conditions were fulfilled:

- The filter pattern is pure hostname
- The filter has not one of the following options:
  - domain
  - denyallow
  - header
  - strict1p, strict3p
  - csp
  - removeparam
- There is a matching exception filter

Related commit:
- a2a8ef7e85

A related mocha test has been added in order to detect this
specific regression in the future through `make test`.

platform/npm/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@gorhill/ubo-core",
-  "version": "0.1.10",
+  "version": "0.1.11",
   "description": "To create a working instance of uBlock Origin's static network filtering engine",
   "type": "module",
   "main": "index.js",

platform/npm/tests/snfe.js

@@ -232,6 +232,24 @@ describe('SNFE', () => {
                     await engine.deserialize(serialized);
                 });
             });
+
+
+            describe('Filter matching', () => {
+                beforeEach(async () => {
+                    engine = await module.StaticNetFilteringEngine.create();
+                });
+
+                it('should match block-important pure-hostname filter', async () => {
+                    await engine.useLists([
+                        { name: 'test', raw: '@@||example.com^\n||example.com^$important' },
+                    ]);
+                    engine.matchRequest({
+                        originURL: 'https://www.example.com/',
+                        type: 'main_frame',
+                        url: 'https://www.example.com/',
+                    });
+                });
+            });
         });
     }
 });

src/js/static-net-filtering.js

@@ -3067,6 +3067,7 @@ class FilterCompiler {
                 break;
             case this.parser.OPTTokenImportant:
                 if ( this.action === AllowAction ) { return false; }
+                this.optionUnitBits |= this.IMPORTANT_BIT;
                 this.action = BlockImportant;
                 break;
             // Used by Adguard:
@@ -3574,14 +3575,15 @@ class FilterCompiler {
     }
 }
 
-FilterCompiler.prototype.DOMAIN_BIT       = 0b00000001;
-FilterCompiler.prototype.DENYALLOW_BIT    = 0b00000010;
-FilterCompiler.prototype.HEADER_BIT       = 0b00000100;
-FilterCompiler.prototype.STRICT_PARTY_BIT = 0b00001000;
-FilterCompiler.prototype.CSP_BIT          = 0b00010000;
-FilterCompiler.prototype.QUERYPRUNE_BIT   = 0b00100000;
-FilterCompiler.prototype.REDIRECT_BIT     = 0b01000000;
-FilterCompiler.prototype.NOT_TYPE_BIT     = 0b10000000;
+FilterCompiler.prototype.DOMAIN_BIT       = 0b000000001;
+FilterCompiler.prototype.DENYALLOW_BIT    = 0b000000010;
+FilterCompiler.prototype.HEADER_BIT       = 0b000000100;
+FilterCompiler.prototype.STRICT_PARTY_BIT = 0b000001000;
+FilterCompiler.prototype.CSP_BIT          = 0b000010000;
+FilterCompiler.prototype.QUERYPRUNE_BIT   = 0b000100000;
+FilterCompiler.prototype.REDIRECT_BIT     = 0b001000000;
+FilterCompiler.prototype.NOT_TYPE_BIT     = 0b010000000;
+FilterCompiler.prototype.IMPORTANT_BIT    = 0b100000000;
 
 FilterCompiler.prototype.FILTER_OK          = 0;
 FilterCompiler.prototype.FILTER_INVALID     = 1;