remove lies_we_tell_hack.hhi from HSL (#83)

Summary:
Pull Request resolved: facebookarchive/fbshipit#83

Pull Request resolved: hhvm/hsl-experimental#76

Pull Request resolved: #98

In HSL and open-source projects that depend on it, most of these "lies" are unneeded, and the remaining places that depend on them can be avoided by changing `\HH\InvariantException` to `InvariantException`. Without namespace, it will always be correctly resolved to wherever HHVM autoimports it from.

"wherever HHVM autoimports it from" is actually changing (it used to be `\InvariantException` but is `\HH\InvariantException` as of a few days ago), which is the reason why this file is problematic. Before the HHVM change, and without the diff, the file was needed -- but after the HHVM change, the file causes Hack errors in HSL and [anything that depends on it](https://travis-ci.org/hhvm/)).

Reviewed By: fredemmott

Differential Revision: D18121499

fbshipit-source-id: abd73c9f72401755ae1250302bb4c515faf23e75

.gitignore

@@ -1,4 +1,5 @@
 vendor/
+*.hhast.parser-cache
 *.swp
 *~
 composer.lock

tests/regex/RegexTest.php

@@ -13,7 +13,6 @@
 
 use function Facebook\FBExpect\expect; // @oss-enable
 use type Facebook\HackTest\{DataProvider, HackTest}; // @oss-enable
-use type HH\InvariantException as InvariantViolationException; // @oss-enable
 
 // @oss-disable: <<Oncalls('hack')>>
 final class RegexTest extends HackTest {
@@ -25,13 +24,15 @@ public static function checkThrowsOnInvalidOffset<T>(
     expect(() ==> $fn('Hello', re"/Hello/", -5))->notToThrow();
     expect(() ==> $fn('Hello', re"/Hello/", 6))->
       toThrow(
-        InvariantViolationException::class,
+        InvariantException::class, // @oss-enable
+        // @oss-disable: InvariantViolationException::class,
         null,
         'Invalid offset should throw an exception',
       );
     expect(() ==> $fn('Hello', re"/Hello/", -6))->
       toThrow(
-        InvariantViolationException::class,
+        InvariantException::class, // @oss-enable
+        // @oss-disable: InvariantViolationException::class,
         null,
         'Invalid offset should throw an exception',
       );
@@ -375,8 +376,10 @@ public function testSplit(
   }
 
   public function testSplitInvalidLimit(): void {
-    expect(() ==> Regex\split('hello world', re"/x/", 1))
-      ->toThrow(InvariantViolationException::class);
+    expect(() ==> Regex\split('hello world', re"/x/", 1))->toThrow(
+      InvariantException::class, // @oss-enable
+      // @oss-disable: InvariantViolationException::class,
+    );
   }
 
   public static function provideToString(