Remove XMLHttpRequestException in favor of DOMException

LayoutTests/http/tests/workers/shared-worker-importScripts-expected.txt

 Test importScripts for SharedWorkers.
 
 Test started.
 PASS: importScripts(), exists, is a function, and doesn't throw when not given any arguments
 Loaded message from different origin
 PASS: executed script from different origin
 Loaded message from different origin
 PASS: executed script from different origin through a redirect
 Testing single argument:
 Loaded resource 1
 PASS: loaded first source
 Testing multiple arguments:
 Loaded resource 1
 Loaded resource 2
 PASS: Both sources loaded and executed.
 Testing multiple arguments (different order):
 Resource 2 loaded before resource 1
 Loaded resource 2
 Loaded resource 1
 PASS: Both sources loaded and executed.
 Testing multiple arguments, with different origin for one argument:
 Loaded resource 1
 Loaded message from different origin
 Loaded resource 2
 PASS: all resources executed.
 Loaded resource 1
-PASS: Threw Error: NETWORK_ERR: XMLHttpRequest Exception 101 when load failed
+PASS: Threw Error: NetworkError: DOM Exception 19 when load failed
 PASS: some resources were loaded despite the network error
 Loaded resource 1
 PASS: Threw SyntaxError: Expected an identifier but found 'syntax' instead when encountering a syntax error in imported script
 PASS: some resources were loaded despite the presence of a syntax error
 Testing multiple arguments, with first resource throwing an exception:
 Loaded resource 1
 First resource throwing an exception
 PASS: Propagated 'Thrown by first resource' from script
 PASS: First resource was executed, and second resource was not
 Testing multiple arguments, with second resource throwing an exception:
 Loaded resource 1
 Loaded resource 2
 Second resource throwing an exception
 PASS: Propagated 'Thrown by second resource' from script
 PASS: Both scripts were executed
 DONE