Issue #1382: Revert "Issue #1337: AbstractIterable now needs to know about the presence of if comprehensions."

This reverts commit b7bacf670b3590f913a7d78c4c91f6deffb07b92.

Conflicts:
	src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java
Issue #1382: Revert "Issue #1351: ExpressionTransformer: Instantiate the AbstractCallable via the CallBuilder, so that we can 'do the Let thing' when there are uninitialized operands stacked and backwards branches."

This reverts commit bda33b67530398b7a6041f1e6df62771a16e46e6.

Conflicts:
	src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java
Issue #1382: Revert "Issue #1351: Partial fix for the dependent Iterable problem, which now exposes a VerifyError when a spread is used as the iterable expression, for example for a comprehension within an initializer section."

This reverts commit 9ff5965496a3bba4058d84bcd1bdfde14e466b3f.

Conflicts:
	src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java
Issue #1382: Revert "Issue #1351: Partial fix by evaluating the underlying Iterable expressions when we instantiate the AbstractIterable, but this doesn't work when an inner for comprehension is over an Iterable that's declared as an iteration variable in an outer comprehension."

This reverts commit 0d4e8df652068da08edda5b6d113193c0f80247b.

Conflicts:
	src/com/redhat/ceylon/compiler/java/codegen/ExpressionTransformer.java
Issue #1382: Fix assertions in Bug1351, now that the semantics have changed.
Issue #1382: @Ignore the test for #1337, due reversion of these changes for #1382
Issue #1382: Bulk update the tests following reversions for the comprehension transformation.
Issue #1382: Add a (simplified) test