fix(nav-bar): set ng-href on nav-item even if md-nav-href is empty (#11488)

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## PR Checklist
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- [x] The commit message follows [our guidelines](https://github.com/angular/material/blob/master/.github/CONTRIBUTING.md#-commit-message-format)
- [x] Tests for the changes have been added or this is not a bug fix / enhancement
- [x] Docs have been added, updated, or were not required

## PR Type
What kind of change does this PR introduce?
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```
[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:
```

## What is the current behavior?
- A new `npm i` may pick up `[email protected]` which will cause many test failures since we don't currently support that version.
- Setting `md-nav-href=""` on an `md-nav-item` doesn't apply the proper `ng-href=""` because of a bad `if` check.
- The docs indicate that a navigation attribute **must** be defined on each `md-nav-item`, but the code doesn't throw an exception if this occurs. This can lead to unexpected behaviors like infinite loops or hanging async tasks.
- The Closure properties are incorrect in a number of cases.

<!-- Please describe the current behavior that you are modifying and link to one or more relevant issues. -->
Issue Number: 
Relates to #11485. Relates to #11486. Fixes #11487.

## What is the new behavior?

- set ng-href on nav-item even if md-nav-href is empty
- fix closure properties to better represent the existing code
- pin the version of jasmine-core since we don't support 2.99.1 yet
- slightly improve the tone of the exceptions
- pull in some karma configuration tweaks from Angular Material

## Does this PR introduce a breaking change?
```
[ ] Yes
[x] No
```
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## Other information

Author: Splaktar

config/karma-sauce.conf.js

@@ -42,7 +42,8 @@ module.exports = function(config) {
       }
     },
 
-    singleRun: true
+    singleRun: true,
+    autoWatch: false
   });
 
 };

config/karma-travis.conf.js

@@ -6,6 +6,8 @@ module.exports = function(config) {
   // Override defaults with custom CI settings
   config.set({
     colors: false,
+    singleRun: true,
+    autoWatch: false,
 
     browsers: ['ChromeHeadlessNoSandbox', 'FirefoxHeadless'],
     customLaunchers: {

config/karma.conf.js

@@ -49,12 +49,17 @@ module.exports = function(config) {
     plugins: [
       require("karma-jasmine"),
       require("karma-chrome-launcher"),
-      require('karma-firefox-launcher')
+      require('karma-firefox-launcher'),
+      require('karma-browserstack-launcher'),
+      require('karma-sauce-launcher')
     ],
     frameworks: ['jasmine'],
     files: dependencies.concat(testSrc),
 
-    browserDisconnectTimeout: 500,
+    browserDisconnectTimeout: 10000,
+    browserDisconnectTolerance: 3,
+    browserNoActivityTimeout: 10000,
+    captureTimeout: 10000,
 
     logLevel: config.LOG_DEBUG,
     port: 9876,
@@ -63,8 +68,16 @@ module.exports = function(config) {
 
     // Continuous Integration mode
     // enable / disable watching file and executing tests whenever any file changes
-    singleRun: true,
-    autoWatch: false,
+    singleRun: false,
+    autoWatch: true,
+
+    // Try Websocket for a faster transmission first. Fallback to polling if necessary.
+    transports: ['websocket', 'polling'],
+
+    browserConsoleLogOptions: {
+      terminal: true,
+      level: 'log'
+    },
 
     // Start these browsers, currently available:
     // - Chrome
@@ -78,7 +91,7 @@ module.exports = function(config) {
 
     client: {
       // Do not clear the context as this can cause reload failures with Jasmine
-      clearContext:false
+      clearContext: false
     }
   });
 };

package-lock.json

@@ -71,7 +71,7 @@
     "gulp-sass": "^4.0.1",
     "gulp-uglify": "^3.0.0",
     "gulp-util": "^3.0.8",
-    "jasmine-core": "^2.2.0",
+    "jasmine-core": "2.8.0",
     "jquery": "^3.3.1",
     "jshint": "^2.9.5",
     "jshint-summary": "^0.4.0",