[WebAssembly] Add some whitespace for clarity

[kripken]

Summary

(Intended as my first commit to LLVM.)

[dschuff]

[tlively]

LGTM!

lib/Target/WebAssembly/WebAssemblyFixIrreducibleControlFlow.cpp

 /// of blocks with a single entry and no branches back to that entry. A region
 /// may be the entire function body, or the inner part of a loop, i.e., the
 /// loop's body without branches back to the loop entry. In each region we fix
 /// up multi-entry loops by adding a new block that can dispatch to each of the
 /// loop entries, based on the value of a label "helper" variable, and we
 /// replace direct branches to the entries with assignments to the label
 /// variable and a branch to the dispatch block. Then the dispatch block is the
 /// single entry in the loop containing the previous multiple entries. After
 /// ensuring all the loops in a region are reducible, we recurse into them. The
 /// total time complexity of this pass is:
+///
 ///   O(NumBlocks * NumNestedLoops * NumIrreducibleLoops +
 ///     NumLoops * NumLoops)
 ///
 /// This pass is similar to what the Relooper [1] does. Both identify looping
 /// code that requires multiple entries, and resolve it in a similar way (in
 /// Relooper terminology, we implement a Multiple shape in a Loop shape). Note
 /// also that like the Relooper, we implement a "minimal" intervention: we only
 /// use the "label" helper for the blocks we absolutely must and no others. We
 /// also prioritize code size and do not duplicate code in order to resolve
 /// irreducibility. The graph algorithms for finding loops and entries and so
 /// forth are also similar to the Relooper. The main differences between this
 /// pass and the Relooper are:
+///
 ///  * We just care about irreducibility, so we just look at loops.
 ///  * The Relooper emits structured control flow (with ifs etc.), while we
 ///    emit a CFG.
 ///
 /// [1] Alon Zakai. 2011. Emscripten: an LLVM-to-JavaScript compiler. In
 /// Proceedings of the ACM international conference companion on Object oriented
 /// programming systems languages and applications companion (SPLASH '11). ACM,
 /// New York, NY, USA, 301-312. DOI=10.1145/2048147.2048224
 /// http://doi.acm.org/10.1145/2048147.2048224
 ///