Remove Emscripten support

test/CodeGen/JS/phi.ll

-; RUN: llc < %s | FileCheck %s
-
-; Phi lowering should check for dependency cycles, including looking through
-; bitcasts, and emit extra copies as needed.
-
-target datalayout = "e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-p:32:32:32-v128:32:128-n32-S128"
-target triple = "asmjs-unknown-emscripten"
-
-; CHECK: while(1) {
-; CHECK:   $k$phi = $j;$j$phi = $k;$k = $k$phi;$j = $j$phi;
-; CHECK: }
-define void @foo(float* nocapture %p, i32* %j.init, i32* %k.init) {
-entry:
-  br label %for.body
-
-for.body:
-  %j = phi i32* [ %j.init, %entry ], [ %k.cast, %more ]
-  %k = phi i32* [ %k.init, %entry ], [ %j.cast, %more ]
-  br label %more
-
-more:
-  %j.cast = bitcast i32* %j to i32*
-  %k.cast = bitcast i32* %k to i32*
-  br label %for.body
-}