Fixes SI-6170: issue with dragging scaladoc splitter over central iframe
Changes Tree and Type members from vals to defs.

Explanatory email:

The reflection API defines a great many abstract vals. I would
like these all to be defs. I'm sending a pull request to that end.

Reasons: for starters, they should default to being defs. It's a
decision to use vals for which one should have to supply reasons.
The reason for THAT is that defs can be implemented with vals, but
not vice versa.

Why does this matter? I can't find my long writing on the subject
of TypeRef. In short, we waste a huge amount of memory on its
fields, because given the way TypeRef is defined, each one demands
a pre, a sym, and an args. Except that somewhere between 1/3 and
1/2 have prefix "NoPrefix", and somewhere between 1/3 and 1/2 have
args "Nil". We know it at creation time, but we give every typeref
the whole field anyway.

At present there's no way to fix this which has acceptable
performance - i.e. custom subclasses save us lots of memory, but
are too much slower for having to use an extractor - but there's
no reason we should have to choose, and I fully expect to fix it
eventually. Let's not make that fix into a breaking change by
abstractly defining "pre" and "args" as field-requiring vals.
SI-6526 Tail call elimination should descend deeper.

It wasn't traversing into Select nodes nor into the receiver of
a tail call.
Fix for SI-6537, inaccurate unchecked warning.

I found a more direct expression of the unchecked logic,
which should be much easier for others to verify.  But the
bug being fixed here is that the unchecked checking happens
too early, and the sealed children of a symbol are not yet
visible if it is being simultaneously compiled.
avoid single-art assert where harmful in duration-tck
Merge pull request #1498 from paulp/defs-not-vals

Changes Tree and Type members from vals to defs.
Merge pull request #1480 from ingoem/topic/scaladoc

Fixes SI-6170: issue with dragging scaladoc splitter over central iframe
Merge pull request #1510 from rkuhn/wip-duration-tck-one-arg-assert

avoid single-arg assert where harmful in duration-tck
Merge pull request #1509 from paulp/issue/6537

Fix for SI-6537, inaccurate unchecked warning.
Fix SI-6552, regression with self types.

In 6eb55d4b7a we put in a remedy for an old issue SI-4560 which
had accumulated a number of sketchy partial remedies which carried
no tests to illustrate their necessity. Looks like at least one of
those was doing something useful. Here's to reversion-reversion.

This reverts commit c8bdf199, which itself reverted cb4fd6582.
SI-6526 Additional test case.
Disabled generation of _1, _2, etc. methods.

This was part of the introduction of ProductN, which had
to go back into pandora's box because of issues with cycles
during typing.  These should have been reverted along
with it.
Merge pull request #1515 from paulp/issue/6552

Fix SI-6552, regression with self types.
Merge pull request #1520 from vigdorchik/drop.phases

Remove compiler phases that don't influence scaladoc generation.
Merge pull request #1507 from retronym/ticket/6526

SI-6526 Tail call elimination should descend deeper.
Merge pull request #1519 from paulp/no-product-n

Disabled generation of _1, _2, etc. methods.
SI-6488: Stop I/O threads prior to Process destruction
SI-6575 Plug inference leak of AbstractPartialFun

Usually this isn't needed, as partial functions can only be
defined with an expected type. But if that expected type is
and inherited method return type, the actual type of the partial
function literal is used, and the implementation detail of
`AbstractPartialFunction[A, B] with Serializable` leaks out.

After this change, the inferred types match those from
Scala 2.9.2.

ticket/6575 ~/code/scala scalac29 -Xprint:typer test/files/pos/t6575a.scala | grep def > 29.txt
ticket/6575 ~/code/scala squalac -Xprint:typer test/files/pos/t6575a.scala | grep def > 210.txt
ticket/6575 ~/code/scala diff -u 29.txt 210.txt
--- 29.txt	2012-10-28 13:51:07.000000000 +0100
+++ 210.txt	2012-10-28 13:51:20.000000000 +0100
@@ -1,7 +1,16 @@
     def foo: PartialFunction[Int,Int]
     def /*Y*/$init$(): Unit = {
-    absoverride def foo: PartialFunction[Int,Int] = ((x0$1: Int) => x0$1 match {
+    absoverride def foo: PartialFunction[Int,Int] = {
+        def <init>(): anonymous class $anonfun = {
+        final override def applyOrElse[A1 >: Nothing <: Int, B1 >: Int <: Any](x$1: A1, default: A1 => B1): B1 = (x$1: A1 @unchecked) match {
+        final def isDefinedAt(x$1: Int): Boolean = (x$1: Int @unchecked) match {
     def /*Z*/$init$(): Unit = {
-    absoverride def foo: PartialFunction[Int,Int] = ((x0$2: Int) => x0$2 match {
+    absoverride def foo: PartialFunction[Int,Int] = {
+        def <init>(): anonymous class $anonfun = {
+        final override def applyOrElse[A1 >: Nothing <: Int, B1 >: Int <: Any](x$1: A1, default: A1 => B1): B1 = (x$1: A1 @unchecked) match {
+        final def isDefinedAt(x$1: Int): Boolean = (x$1: Int @unchecked) match {
     def /*Comb*/$init$(): Unit = {
-    absoverride def foo: PartialFunction[Int,Int] = ((x0$3: Int) => x0$3 match {
+    absoverride def foo: PartialFunction[Int,Int] = {
+        def <init>(): anonymous class $anonfun = {
+        final override def applyOrElse[A1 >: Nothing <: Int, B1 >: Int <: Any](x$1: A1, default: A1 => B1): B1 = (x$1: A1 @unchecked) match {
+        final def isDefinedAt(x$1: Int): Boolean = (x$1: Int @unchecked) match {
Wider use and a new variant of typedPos.

It's safe to replace `localTyper.typed(atPos(pos)(tree))` with
`localTyper.typedPos(pos)(tree)` given that we're all in the
same cake and we'll get to the same `atPos`.
Use Typed rather than .setType

In response to pull request feedback.