Worklet: Specify JavaScript MIME type for Worklets created from Blob URL

third_party/WebKit/LayoutTests/csspaint/resources/test-runner-invalidation-logging.js

 // Test runner for the paint worklet to test invalidation behaviour.
 //
 // Registers an promise_test per test case, which:
 //  - Creates an element.
 //  - Invalidates the style of that element.
 //  - [worklet] Worklet code logs if it got the invalidation.
 //  - Asserts that it got the correct paint invalidation.
 //
 // Usage:
 // testRunnerInvalidationLogging('background-image', [
@@ skipping 14 matching lines @@
                     ctx.fillRect(0, 0, geom.width, geom.height);
                     if (this.hasPainted) {
                         console.log('Successful invalidation for: ' + properties[i]);
                     }
                     this.hasPainted = true;
                 }
             });
         }
     `;
 
-    paintWorklet.addModule(URL.createObjectURL(new Blob([workletCode]))).then(function() {
+    paintWorklet.addModule(URL.createObjectURL(new Blob([workletCode], {type: 'text/javascript'}))).then(function() {
         for (let i = 0; i < tests.length; i++) {
             tests[i].paintName = 'paint-' + i;
             registerTest(imageType, tests[i]);
         }
     });
 }
 
 function registerTest(imageType, test) {
     const testName = test.property + ': ' + (test.prevValue || '[inline not set]') + ' => ' + (test.invalidationProperty || test.property) + ': ' + (test.value || '[inline not set]');
 
@@ skipping 46 matching lines @@
                     // Cleanup.
                     document.body.removeChild(el);
                     resolve();
                 });
             });
 
         });
 
     }, testName);
 }