Suggest 'var' type variables as auto-completion method arguments. Fix #228

[hotspotoq]

What it does

• Fixes 'var' types are not suggested as auto-completion method arguments  #228

Uses existing logic which has been commented out.

The condition local.declaration.initialization != null matches with variables being initialized but also matches var declarations. Then var variables get out of completion candidates. Fortunately, there was existing logic in code's comments that can deal with this problem.

This simple changes also fix this issue but are not perfect here. (The problem is that var variables being initialized will appear in proposals, but can this change be better choice?)
78adf91f002a1a9b7d1838c24de08c2d5f608e25

Provides resolved types of var declarations.

When calculating auto-boxing scores, var is considered qualified class type whose name is var. Without the change, primitive type variables declared with var get bad scores; the auto-completion suggests 0 of literal instead of var variables. This change is same as: 3b1eade6257846b964d26359bdcfbc40d6c4bec4

Uses the method with null checks and adds an argument.

I believe it should have null checks. local.declaringScope is used to tell whether var keyword is available at the version.

How to test

eclipse.jdt.ui/org.eclipse.jdt.text.tests/src/org/eclipse/jdt/text/tests/contentassist/MethodParameterGuessingCompletionTest10.java
eclipse.jdt.ui/org.eclipse.jdt.text.tests/src/org/eclipse/jdt/text/tests/contentassist/CompletionTestSetup10.java
These tests will have to be situated in eclipse.jdt.ui, what can I do?

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

I'm open to changing expressions since I'm not good at English.