[Reland] Implement test cases for blink::VectorMath functions

Original CL: https://chromium-review.googlesource.com/737877

This CL avoids erroneous array bound checks in the standard algorithm
library.

This is a preparation for AVX optimization of blink::VectorMath
functions.

Bug: 778262
Change-Id: Ifc8465644a048cd0815c993dd824bdf62d04415a
Reviewed-on: https://chromium-review.googlesource.com/744005Reviewed-by: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Eero Häkkinen <eero.hakkinen@intel.com>
Cr-Commit-Position: refs/heads/master@{#512674}

third_party/WebKit/Source/platform/BUILD.gn

@@ -1736,6 +1736,7 @@ jumbo_source_set("blink_platform_unittests_sources") {
     "animation/CompositorFloatAnimationCurveTest.cpp",
     "animation/TimingFunctionTest.cpp",
     "audio/PushPullFIFOTest.cpp",
+    "audio/VectorMathTest.cpp",
     "bindings/RuntimeCallStatsTest.cpp",
     "exported/FilePathConversionTest.cpp",
     "exported/WebCORSPreflightResultCacheTest.cpp",