Use JDT static inner class clean up for
text plug-ins

This ticket uses and tests the "Use static inner class" cleanup feature:
 - It reviews the feature
 - It reduces the memory consumption as it avoids the pointer to the
outer class

Example:

Before:

public class Outer {

public class InnerClass {
    int i;

    public boolean anotherMethod() {
        return true;
    }
}
}

After:

public class Outer {

public static class InnerClass {
    int i;

    public boolean anotherMethod() {
        return true;
    }
}
}

Change-Id: Ife8c2036dbdd0cdbebdd952b603c2fceeb2ccd58
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.text/+/180219
Tested-by: Platform Bot <platform-bot@eclipse.org>
diff --git a/org.eclipse.core.filebuffers.tests/src/org/eclipse/core/filebuffers/tests/FileBufferFunctions.java b/org.eclipse.core.filebuffers.tests/src/org/eclipse/core/filebuffers/tests/FileBufferFunctions.java
index 9219d2e..d3edd24 100644
--- a/org.eclipse.core.filebuffers.tests/src/org/eclipse/core/filebuffers/tests/FileBufferFunctions.java
+++ b/org.eclipse.core.filebuffers.tests/src/org/eclipse/core/filebuffers/tests/FileBufferFunctions.java
@@ -106,7 +106,7 @@
 	@Rule
 	public TestFailReporter failReporter= new TestFailReporter();
 
-	public class TestFailReporter extends TestWatcher {
+	public static class TestFailReporter extends TestWatcher {
 
 		private static final String BUNDLE_ID= "org.eclipse.core.filebuffers.tests";