IntelliJ not highlighting some dartdoc links, even though it knows what they should be.

## Steps to Reproduce

I added a "See also" item to the dartdoc for the Paint object in the flutter engine, and the existing dartdoc had the text `[StrokeJoin.miter]` in it, and it was highlighted and linked, but when I added the same link in my new text, it wasn't highlighted and linked.


This seems like a bug: the same context can't find the link that it clearly knows about somewhere. I tried copy/pasting the one that works and pasting it where the new one is (to make sure I wasn't somehow typing something different), and it still didn't link.

## Version info

```
[✓] Flutter (Channel unknown, v0.5.2-pre.47, on Linux, locale en_US.UTF-8)
• Flutter version 0.5.2-pre.47 at /usr/local/google/home/gspencer/code/flutter
• Framework revision 43da9d5ef9 (6 hours ago), 2018-06-04 17:59:07 +0100
• Engine revision 6cef519598
• Dart version 2.0.0-dev.59.0.flutter-1a185867a9

[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
• Android SDK at /usr/local/google/home/gspencer/Android/Sdk
• Android NDK at /usr/local/google/home/gspencer/Android/Sdk/ndk-bundle
• Platform android-27, build-tools 27.0.3
• ANDROID_HOME = /usr/local/google/home/gspencer/Android/Sdk
• Java binary at: /opt/android-studio-with-blaze-3.0/jre/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-915-b01)
• All Android licenses accepted.

[✓] IntelliJ IDEA Community Edition (version 2018.1)
• IntelliJ at /opt/my-intellij-ce-2018.1
• Flutter plugin version 25.0.2
• Dart plugin version 181.4892.1

[✓] Connected devices (1 available)
• Nexus 6P • 84B7N15A07007628 • android-arm64 • Android 8.1.0 (API 27)

• No issues found!
```

Start by reproducing the issue in IntelliJ IDEA 2018.1 with the listed Flutter and Dart plugin versions, comparing the existing and newly added dartdoc links in the Paint documentation. Trace the IntelliJ or Dart plugin handling for dartdoc link highlighting; done means equivalent links are consistently highlighted and navigable.

Written by the indexing model from the issue text.