Fix some more typos, this time words that are duplicated.

src/libcore/ops/unsize.rs

@@ -24,7 +24,7 @@ use marker::Unsize;
 /// Such an impl can only be written if `Foo<T>` has only a single non-phantomdata
 /// field involving `T`. If the type of that field is `Bar<T>`, an implementation
 /// of `CoerceUnsized<Bar<U>> for Bar<T>` must exist. The coercion will work by
-/// by coercing the `Bar<T>` field into `Bar<U>` and filling in the rest of the fields
+/// coercing the `Bar<T>` field into `Bar<U>` and filling in the rest of the fields
 /// from `Foo<T>` to create a `Foo<U>`. This will effectively drill down to a pointer
 /// field and coerce that.
 ///

src/libproc_macro/lib.rs

@@ -111,7 +111,7 @@ impl fmt::Display for TokenStream {
 
 /// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
 /// For example, `quote!(a + b)` will produce a expression, that, when evaluated, constructs
-/// constructs the `TokenStream` `[Word("a"), Op('+', Alone), Word("b")]`.
+/// the `TokenStream` `[Word("a"), Op('+', Alone), Word("b")]`.
 ///
 /// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
 /// To quote `$` itself, use `$$`.

src/librustc_driver/driver.rs

@@ -282,7 +282,7 @@ pub fn source_name(input: &Input) -> String {
 /// This is a somewhat higher level controller than a Session - the Session
 /// controls what happens in each phase, whereas the CompileController controls
 /// whether a phase is run at all and whether other code (from outside the
-/// the compiler) is run between phases.
+/// compiler) is run between phases.
 ///
 /// Note that if compilation is set to stop and a callback is provided for a
 /// given entry point, the callback is called before compilation is stopped.