fix(language-service): remove tsickle dependency

Removes the tsickle dependency added when tsickle was added to the
transform compiler.

Added a test to ensure stray dependencies are not added and no
errors are introduced during module flattening.

integration/language_service_plugin/tools/load_test.ts

@@ -0,0 +1,35 @@
+const ts = require('typescript');
+const Module = require('module');
+
+const existingRequire = Module.prototype.require;
+
+const recordedRequires: string[] = [];
+
+function recordingRequire(path: string) {
+  recordedRequires.push(path);
+  return existingRequire.call(this, path);
+}
+
+Module.prototype.require = recordingRequire;
+
+try {
+  const lsf = require('@angular/language-service');
+  const ls = lsf({typescript: ts});
+
+  // Assert that the only module that should have been required are '@angular/langauge-service', 'fs', and 'path'
+
+  const allowedLoads = new Set(["@angular/language-service", "fs", "path"]);
+
+  const invalidModules = recordedRequires.filter(m => !allowedLoads.has(m));
+
+  if (invalidModules.length > 0) {
+    console.error(`FAILED: Loading the language service required: ${invalidModules.join(', ')}`);
+    process.exit(1);
+  }
+} catch (e) {
+  console.error(`FAILED: Loading the language service caused the following exception: ${e.stack || e}`);
+  process.exit(1);
+}
+
+console.log('SUCCESS: Loading passed')
+process.exit(0);