Rolling 4 dependencies

Roll third_party/SPIRV-Tools/ 9eb1c9a4c..253806adc (20 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools/+log/9eb1c9a4c450..253806adc4c6

$ git log 9eb1c9a4c..253806adc --date=short --no-merges --format='%ad %ae %s'
2019-10-10 afdx spirv-fuzz: Add fuzzer pass to change loop controls (#2949)
2019-10-10 afdx Fixed include paths and order according to Google style. (#2957)
2019-10-09 ehsannas Use a longer timeout for Bazel tests. (#2956)
2019-10-09 rharrison Remove non-existent files from BUILD.gn (#2955)
2019-10-09 alanbaker Disable scope validation for OpReadClockKHR (#2953)
2019-10-09 cwallez CMake: Add support for building with emscripten (#2948)
2019-10-09 stevenperron Update CHANGES
2019-10-08 stevenperron Link cfg and dominator analysis in the context (#2946)
2019-10-08 afdx spirv-fuzz: add transformation and pass to construct composites (#2941)
2019-10-08 paulthomson reduce: improve remove unref instr pass (#2945)
2019-10-08 afdx spirv-fuzz: add disabled test to document known issue (#2942)
2019-10-08 afdx spirv-fuzz: Add fuzzer pass to change selection controls (#2944)
2019-10-07 jeremy-lunarg Enable OpTypeCooperativeMatrix specialization (#2927)
2019-10-04 stevenperron Handle OpKill better (#2933)
2019-10-04 greg Generate null pointer by converting uint64 zero to pointer. (#2935)
2019-10-03 afdx spirv-fuzz: option to convert shader into a form that renders red (#2934)
2019-10-03 32110296+AaronHaganAMD Add SPV_KHR_shader_clock validation (#2879)
2019-10-03 paulthomson reduce/fuzz: improve command line args (#2932)
2019-10-02 alanbaker Validate physical storage buffer restrictions (#2930)
2019-10-01 paulthomson fuzz: add shrinker-temp-file-prefix (#2928)

Roll third_party/glslang/ 7bc047326..4b97a1108 (5 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/glslang/+log/7bc047326e06..4b97a1108114

$ git log 7bc047326..4b97a1108 --date=short --no-merges --format='%ad %ae %s'
2019-10-06 dj2 single line
2019-10-03 dj2 Update appveyor and travis files
2019-10-03 dj2 Move install directory for SPIRV/ folder.
2019-09-29 cepheus HLSL: Fix #1912: add attribute syntax for nonreadable/nonwritable
2019-09-27 cepheus HLSL: Fix #1912: add attribute syntax for overriding image formats.

Roll third_party/shaderc/ 621605ce2..65adcb504 (3 commits)

https://chromium.googlesource.com/external/github.com/google/shaderc/+log/621605ce2644..65adcb504d02

$ git log 621605ce2..65adcb504 --date=short --no-merges --format='%ad %ae %s'
2019-10-09 rharrison Add in shaderc_features.gni to support build time flags (#837)
2019-10-09 rharrison Rolling 5 dependencies (#836)
2019-10-09 rharrison Add spvc compiler to returned result (#828)

Roll third_party/spirv-headers/ 842ec9067..b252a5095 (1 commit)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Headers/+log/842ec9067462..b252a50953ac

$ git log 842ec9067..b252a5095 --date=short --no-merges --format='%ad %ae %s'
2019-09-24 lukasz.gotszald add cmake option SPIRV_HEADERS_SKIP_INSTALL

Created with:
  roll-dep third_party/SPIRV-Tools third_party/glslang third_party/shaderc third_party/spirv-cross third_party/spirv-headers

Change-Id: I19a3d341592605350e9f3e9d16aa60d0893d75bc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12060
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/DEPS b/DEPS
index 2d76319..150de86 100644
--- a/DEPS
+++ b/DEPS
@@ -56,19 +56,19 @@
 
   # SPIRV compiler dependencies: SPIRV-Tools, SPIRV-headers, glslang and shaderc
   'third_party/SPIRV-Tools': {
-    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Tools@9eb1c9a4c45099c23098d97c5a6a8b35a45a8f25',
+    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Tools@253806adc4c654c087ffe1e8e64b538d00989b16',
     'condition': 'dawn_standalone',
   },
   'third_party/spirv-headers': {
-    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Headers@842ec90674627ed2ffef609e3cd79d1562eded01',
+    'url': '{chromium_git}/external/github.com/KhronosGroup/SPIRV-Headers@b252a50953ac4375cb1864e94f4b0234db9d215d',
     'condition': 'dawn_standalone',
   },
   'third_party/glslang': {
-    'url': '{chromium_git}/external/github.com/KhronosGroup/glslang@7bc047326e06961c59b785f827026947d81c7f02',
+    'url': '{chromium_git}/external/github.com/KhronosGroup/glslang@4b97a1108114107a8082a55e9e0721a40f9536d3',
     'condition': 'dawn_standalone',
   },
   'third_party/shaderc': {
-    'url': '{chromium_git}/external/github.com/google/shaderc@621605ce2644d55ab74cb27a8afef97dc40f1b0f',
+    'url': '{chromium_git}/external/github.com/google/shaderc@65adcb504d024bb29f0ad8279b6a215d5f679832',
     'condition': 'dawn_standalone',
   },